In the Linux kernel, the following vulnerability has been resolved:
ax25: Remove broken autobind
Binding AX25 socket by using the autobind feature leads to memory leaks
in ax25_connect() and also refcount leaks in ax25_release(). Memory
leak was detected with kmemleak:
================================================================
unreferenced object 0xffff8880253cd680 (size 96):
backtrace:
__kmalloc_node_track_caller_noprof (./include/linux/kmemleak.h:43)
kmemdup_noprof (mm/util.c:136)
ax25_rt_autobind (net/ax25/ax25_route.c:428)
ax25_connect (net/ax25/af_ax25.c:1282)
__sys_connect_file (net/socket.c:2045)
__sys_connect (net/socket.c:2064)
__x64_sys_connect (net/socket.c:2067)
do_syscall_64 (arch/x86/entry/common.c:52 arch/x86/entry/common.c:83)
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
================================================================
When socket is bound, refcounts must be incremented the way it is done
in ax25_bind() and ax25_setsockopt() (SO_BINDTODEVICE). In case of
autobind, the refcounts are not incremented.
This bug leads to the following issue reported by Syzkaller:
================================================================
ax25_connect(): syz-executor318 uses autobind, please contact jreuter@yaina.de
------------[ cut here ]------------
refcount_t: decrement hit 0; leaking memory.
WARNING: CPU: 0 PID: 5317 at lib/refcount.c:31 refcount_warn_saturate+0xfa/0x1d0 lib/refcount.c:31
Modules linked in:
CPU: 0 UID: 0 PID: 5317 Comm: syz-executor318 Not tainted 6.14.0-rc4-syzkaller-00278-gece144f151ac #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:refcount_warn_saturate+0xfa/0x1d0 lib/refcount.c:31
...
Call Trace:
<TASK>
__refcount_dec include/linux/refcount.h:336 [inline]
refcount_dec include/linux/refcount.h:351 [inline]
ref_tracker_free+0x6af/0x7e0 lib/ref_tracker.c:236
netdev_tracker_free include/linux/netdevice.h:4302 [inline]
netdev_put include/linux/netdevice.h:4319 [inline]
ax25_release+0x368/0x960 net/ax25/af_ax25.c:1080
__sock_release net/socket.c:647 [inline]
sock_close+0xbc/0x240 net/socket.c:1398
__fput+0x3e9/0x9f0 fs/file_table.c:464
__do_sys_close fs/open.c:1580 [inline]
__se_sys_close fs/open.c:1565 [inline]
__x64_sys_close+0x7f/0x110 fs/open.c:1565
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
...
</TASK>
================================================================
Considering the issues above and the comments left in the code that say:
"check if we can remove this feature. It is broken."; "autobinding in this
may or may not work"; - it is better to completely remove this feature than
to fix it because it is broken and leads to various kinds of memory bugs.
Now calling connect() without first binding socket will result in an
error (-EINVAL). Userspace software that relies on the autobind feature
might get broken. However, this feature does not seem widely used with
this specific driver as it was not reliable at any point of time, and it
is already broken anyway. E.g. ax25-tools and ax25-apps packages for
popular distributions do not use the autobind feature for AF_AX25.
Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
In the Linux kernel, the following vulnerability has been resolved:
bnxt_en: Mask the bd_cnt field in the TX BD properly
The bd_cnt field in the TX BD specifies the total number of BDs for
the TX packet. The bd_cnt field has 5 bits and the maximum number
supported is 32 with the value 0.
CONFIG_MAX_SKB_FRAGS can be modified and the total number of SKB
fragments can approach or exceed the maximum supported by the chip.
Add a macro to properly mask the bd_cnt field so that the value 32
will be properly masked and set to 0 in the bd_cnd field.
Without this patch, the out-of-range bd_cnt value will corrupt the
TX BD and may cause TX timeout.
The next patch will check for values exceeding 32.
In the Linux kernel, the following vulnerability has been resolved:
net: dsa: sja1105: fix kasan out-of-bounds warning in sja1105_table_delete_entry()
There are actually 2 problems:
- deleting the last element doesn't require the memmove of elements
[i + 1, end) over it. Actually, element i+1 is out of bounds.
- The memmove itself should move size - i - 1 elements, because the last
element is out of bounds.
The out-of-bounds element still remains out of bounds after being
accessed, so the problem is only that we touch it, not that it becomes
in active use. But I suppose it can lead to issues if the out-of-bounds
element is part of an unmapped page.
In the Linux kernel, the following vulnerability has been resolved:
vmxnet3: unregister xdp rxq info in the reset path
vmxnet3 does not unregister xdp rxq info in the
vmxnet3_reset_work() code path as vmxnet3_rq_destroy()
is not invoked in this code path. So, we get below message with a
backtrace.
Missing unregister, handled but fix driver
WARNING: CPU:48 PID: 500 at net/core/xdp.c:182
__xdp_rxq_info_reg+0x93/0xf0
This patch fixes the problem by moving the unregister
code of XDP from vmxnet3_rq_destroy() to vmxnet3_rq_cleanup().
In the Linux kernel, the following vulnerability has been resolved:
bonding: check xdp prog when set bond mode
Following operations can trigger a warning[1]:
ip netns add ns1
ip netns exec ns1 ip link add bond0 type bond mode balance-rr
ip netns exec ns1 ip link set dev bond0 xdp obj af_xdp_kern.o sec xdp
ip netns exec ns1 ip link set bond0 type bond mode broadcast
ip netns del ns1
When delete the namespace, dev_xdp_uninstall() is called to remove xdp
program on bond dev, and bond_xdp_set() will check the bond mode. If bond
mode is changed after attaching xdp program, the warning may occur.
Some bond modes (broadcast, etc.) do not support native xdp. Set bond mode
with xdp program attached is not good. Add check for xdp program when set
bond mode.
[1]
------------[ cut here ]------------
WARNING: CPU: 0 PID: 11 at net/core/dev.c:9912 unregister_netdevice_many_notify+0x8d9/0x930
Modules linked in:
CPU: 0 UID: 0 PID: 11 Comm: kworker/u4:0 Not tainted 6.14.0-rc4 #107
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.15.0-0-g2dd4b9b3f840-prebuilt.qemu.org 04/01/2014
Workqueue: netns cleanup_net
RIP: 0010:unregister_netdevice_many_notify+0x8d9/0x930
Code: 00 00 48 c7 c6 6f e3 a2 82 48 c7 c7 d0 b3 96 82 e8 9c 10 3e ...
RSP: 0018:ffffc90000063d80 EFLAGS: 00000282
RAX: 00000000ffffffa1 RBX: ffff888004959000 RCX: 00000000ffffdfff
RDX: 0000000000000000 RSI: 00000000ffffffea RDI: ffffc90000063b48
RBP: ffffc90000063e28 R08: ffffffff82d39b28 R09: 0000000000009ffb
R10: 0000000000000175 R11: ffffffff82d09b40 R12: ffff8880049598e8
R13: 0000000000000001 R14: dead000000000100 R15: ffffc90000045000
FS: 0000000000000000(0000) GS:ffff888007a00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000d406b60 CR3: 000000000483e000 CR4: 00000000000006f0
Call Trace:
<TASK>
? __warn+0x83/0x130
? unregister_netdevice_many_notify+0x8d9/0x930
? report_bug+0x18e/0x1a0
? handle_bug+0x54/0x90
? exc_invalid_op+0x18/0x70
? asm_exc_invalid_op+0x1a/0x20
? unregister_netdevice_many_notify+0x8d9/0x930
? bond_net_exit_batch_rtnl+0x5c/0x90
cleanup_net+0x237/0x3d0
process_one_work+0x163/0x390
worker_thread+0x293/0x3b0
? __pfx_worker_thread+0x10/0x10
kthread+0xec/0x1e0
? __pfx_kthread+0x10/0x10
? __pfx_kthread+0x10/0x10
ret_from_fork+0x2f/0x50
? __pfx_kthread+0x10/0x10
ret_from_fork_asm+0x1a/0x30
</TASK>
---[ end trace 0000000000000000 ]---
In the Linux kernel, the following vulnerability has been resolved:
ibmvnic: Use kernel helpers for hex dumps
Previously, when the driver was printing hex dumps, the buffer was cast
to an 8 byte long and printed using string formatters. If the buffer
size was not a multiple of 8 then a read buffer overflow was possible.
Therefore, create a new ibmvnic function that loops over a buffer and
calls hex_dump_to_buffer instead.
This patch address KASAN reports like the one below:
ibmvnic 30000003 env3: Login Buffer:
ibmvnic 30000003 env3: 01000000af000000
<...>
ibmvnic 30000003 env3: 2e6d62692e736261
ibmvnic 30000003 env3: 65050003006d6f63
==================================================================
BUG: KASAN: slab-out-of-bounds in ibmvnic_login+0xacc/0xffc [ibmvnic]
Read of size 8 at addr c0000001331a9aa8 by task ip/17681
<...>
Allocated by task 17681:
<...>
ibmvnic_login+0x2f0/0xffc [ibmvnic]
ibmvnic_open+0x148/0x308 [ibmvnic]
__dev_open+0x1ac/0x304
<...>
The buggy address is located 168 bytes inside of
allocated 175-byte region [c0000001331a9a00, c0000001331a9aaf)
<...>
=================================================================
ibmvnic 30000003 env3: 000000000033766e
In the Linux kernel, the following vulnerability has been resolved:
net: fix NULL pointer dereference in l3mdev_l3_rcv
When delete l3s ipvlan:
ip link del link eth0 ipvlan1 type ipvlan mode l3s
This may cause a null pointer dereference:
Call trace:
ip_rcv_finish+0x48/0xd0
ip_rcv+0x5c/0x100
__netif_receive_skb_one_core+0x64/0xb0
__netif_receive_skb+0x20/0x80
process_backlog+0xb4/0x204
napi_poll+0xe8/0x294
net_rx_action+0xd8/0x22c
__do_softirq+0x12c/0x354
This is because l3mdev_l3_rcv() visit dev->l3mdev_ops after
ipvlan_l3s_unregister() assign the dev->l3mdev_ops to NULL. The process
like this:
(CPU1) | (CPU2)
l3mdev_l3_rcv() |
check dev->priv_flags: |
master = skb->dev; |
|
| ipvlan_l3s_unregister()
| set dev->priv_flags
| dev->l3mdev_ops = NULL;
|
visit master->l3mdev_ops |
To avoid this by do not set dev->l3mdev_ops when unregister l3s ipvlan.
In the Linux kernel, the following vulnerability has been resolved:
net: libwx: fix Tx L4 checksum
The hardware only supports L4 checksum offload for TCP/UDP/SCTP protocol.
There was a bug to set Tx checksum flag for the other protocol that results
in Tx ring hang. Fix to compute software checksum for these packets.
In the Linux kernel, the following vulnerability has been resolved:
drm/panthor: Fix race condition when gathering fdinfo group samples
Commit e16635d88fa0 ("drm/panthor: add DRM fdinfo support") failed to
protect access to groups with an xarray lock, which could lead to
use-after-free errors.
In the Linux kernel, the following vulnerability has been resolved:
drm: xlnx: zynqmp_dpsub: Add NULL check in zynqmp_audio_init
devm_kasprintf() calls can return null pointers on failure.
But some return values were not checked in zynqmp_audio_init().
Add NULL check in zynqmp_audio_init(), avoid referencing null
pointers in the subsequent code.
In the Linux kernel, the following vulnerability has been resolved:
drm: zynqmp_dp: Fix a deadlock in zynqmp_dp_ignore_hpd_set()
Instead of attempting the same mutex twice, lock and unlock it.
This bug has been detected by the Clang thread-safety analyzer.
In the Linux kernel, the following vulnerability has been resolved:
drm/vkms: Fix use after free and double free on init error
If the driver initialization fails, the vkms_exit() function might
access an uninitialized or freed default_config pointer and it might
double free it.
Fix both possible errors by initializing default_config only when the
driver initialization succeeded.
In the Linux kernel, the following vulnerability has been resolved:
drm/msm/gem: Fix error code msm_parse_deps()
The SUBMIT_ERROR() macro turns the error code negative. This extra '-'
operation turns it back to positive EINVAL again. The error code is
passed to ERR_PTR() and since positive values are not an IS_ERR() it
eventually will lead to an oops. Delete the '-'.
Patchwork: https://patchwork.freedesktop.org/patch/637625/
In the Linux kernel, the following vulnerability has been resolved:
PCI: brcmstb: Fix error path after a call to regulator_bulk_get()
If the regulator_bulk_get() returns an error and no regulators
are created, we need to set their number to zero.
If we don't do this and the PCIe link up fails, a call to the
regulator_bulk_free() will result in a kernel panic.
While at it, print the error value, as we cannot return an error
upwards as the kernel will WARN() on an error from add_bus().
[kwilczynski: commit log, use comma in the message to match style with
other similar messages]
In the Linux kernel, the following vulnerability has been resolved:
powerpc/perf: Fix ref-counting on the PMU 'vpa_pmu'
Commit 176cda0619b6 ("powerpc/perf: Add perf interface to expose vpa
counters") introduced 'vpa_pmu' to expose Book3s-HV nested APIv2 provided
L1<->L2 context switch latency counters to L1 user-space via
perf-events. However the newly introduced PMU named 'vpa_pmu' doesn't
assign ownership of the PMU to the module 'vpa_pmu'. Consequently the
module 'vpa_pmu' can be unloaded while one of the perf-events are still
active, which can lead to kernel oops and panic of the form below on a
Pseries-LPAR:
BUG: Kernel NULL pointer dereference on read at 0x00000058
<snip>
NIP [c000000000506cb8] event_sched_out+0x40/0x258
LR [c00000000050e8a4] __perf_remove_from_context+0x7c/0x2b0
Call Trace:
[c00000025fc3fc30] [c00000025f8457a8] 0xc00000025f8457a8 (unreliable)
[c00000025fc3fc80] [fffffffffffffee0] 0xfffffffffffffee0
[c00000025fc3fcd0] [c000000000501e70] event_function+0xa8/0x120
<snip>
Kernel panic - not syncing: Aiee, killing interrupt handler!
Fix this by adding the module ownership to 'vpa_pmu' so that the module
'vpa_pmu' is ref-counted and prevented from being unloaded when perf-events
are initialized.
In the Linux kernel, the following vulnerability has been resolved:
PCI: Fix NULL dereference in SR-IOV VF creation error path
Clean up when virtfn setup fails to prevent NULL pointer dereference
during device removal. The kernel oops below occurred due to incorrect
error handling flow when pci_setup_device() fails.
Add pci_iov_scan_device(), which handles virtfn allocation and setup and
cleans up if pci_setup_device() fails, so pci_iov_add_virtfn() doesn't need
to call pci_stop_and_remove_bus_device(). This prevents accessing
partially initialized virtfn devices during removal.
BUG: kernel NULL pointer dereference, address: 00000000000000d0
RIP: 0010:device_del+0x3d/0x3d0
Call Trace:
pci_remove_bus_device+0x7c/0x100
pci_iov_add_virtfn+0xfa/0x200
sriov_enable+0x208/0x420
mlx5_core_sriov_configure+0x6a/0x160 [mlx5_core]
sriov_numvfs_store+0xae/0x1a0
[bhelgaas: commit log, return ERR_PTR(-ENOMEM) directly]
In the Linux kernel, the following vulnerability has been resolved:
x86/mm/pat: Fix VM_PAT handling when fork() fails in copy_page_range()
If track_pfn_copy() fails, we already added the dst VMA to the maple
tree. As fork() fails, we'll cleanup the maple tree, and stumble over
the dst VMA for which we neither performed any reservation nor copied
any page tables.
Consequently untrack_pfn() will see VM_PAT and try obtaining the
PAT information from the page table -- which fails because the page
table was not copied.
The easiest fix would be to simply clear the VM_PAT flag of the dst VMA
if track_pfn_copy() fails. However, the whole thing is about "simply"
clearing the VM_PAT flag is shaky as well: if we passed track_pfn_copy()
and performed a reservation, but copying the page tables fails, we'll
simply clear the VM_PAT flag, not properly undoing the reservation ...
which is also wrong.
So let's fix it properly: set the VM_PAT flag only if the reservation
succeeded (leaving it clear initially), and undo the reservation if
anything goes wrong while copying the page tables: clearing the VM_PAT
flag after undoing the reservation.
Note that any copied page table entries will get zapped when the VMA will
get removed later, after copy_page_range() succeeded; as VM_PAT is not set
then, we won't try cleaning VM_PAT up once more and untrack_pfn() will be
happy. Note that leaving these page tables in place without a reservation
is not a problem, as we are aborting fork(); this process will never run.
A reproducer can trigger this usually at the first try:
https://gitlab.com/davidhildenbrand/scratchspace/-/raw/main/reproducers/pat_fork.c
WARNING: CPU: 26 PID: 11650 at arch/x86/mm/pat/memtype.c:983 get_pat_info+0xf6/0x110
Modules linked in: ...
CPU: 26 UID: 0 PID: 11650 Comm: repro3 Not tainted 6.12.0-rc5+ #92
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-2.fc40 04/01/2014
RIP: 0010:get_pat_info+0xf6/0x110
...
Call Trace:
<TASK>
...
untrack_pfn+0x52/0x110
unmap_single_vma+0xa6/0xe0
unmap_vmas+0x105/0x1f0
exit_mmap+0xf6/0x460
__mmput+0x4b/0x120
copy_process+0x1bf6/0x2aa0
kernel_clone+0xab/0x440
__do_sys_clone+0x66/0x90
do_syscall_64+0x95/0x180
Likely this case was missed in:
d155df53f310 ("x86/mm/pat: clear VM_PAT if copy_p4d_range failed")
... and instead of undoing the reservation we simply cleared the VM_PAT flag.
Keep the documentation of these functions in include/linux/pgtable.h,
one place is more than sufficient -- we should clean that up for the other
functions like track_pfn_remap/untrack_pfn separately.
In the Linux kernel, the following vulnerability has been resolved:
RDMA/core: Don't expose hw_counters outside of init net namespace
Commit 467f432a521a ("RDMA/core: Split port and device counter sysfs
attributes") accidentally almost exposed hw counters to non-init net
namespaces. It didn't expose them fully, as an attempt to read any of
those counters leads to a crash like this one:
[42021.807566] BUG: kernel NULL pointer dereference, address: 0000000000000028
[42021.814463] #PF: supervisor read access in kernel mode
[42021.819549] #PF: error_code(0x0000) - not-present page
[42021.824636] PGD 0 P4D 0
[42021.827145] Oops: 0000 [#1] SMP PTI
[42021.830598] CPU: 82 PID: 2843922 Comm: switchto-defaul Kdump: loaded Tainted: G S W I XXX
[42021.841697] Hardware name: XXX
[42021.849619] RIP: 0010:hw_stat_device_show+0x1e/0x40 [ib_core]
[42021.855362] Code: 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 0f 1f 44 00 00 49 89 d0 4c 8b 5e 20 48 8b 8f b8 04 00 00 48 81 c7 f0 fa ff ff <48> 8b 41 28 48 29 ce 48 83 c6 d0 48 c1 ee 04 69 d6 ab aa aa aa 48
[42021.873931] RSP: 0018:ffff97fe90f03da0 EFLAGS: 00010287
[42021.879108] RAX: ffff9406988a8c60 RBX: ffff940e1072d438 RCX: 0000000000000000
[42021.886169] RDX: ffff94085f1aa000 RSI: ffff93c6cbbdbcb0 RDI: ffff940c7517aef0
[42021.893230] RBP: ffff97fe90f03e70 R08: ffff94085f1aa000 R09: 0000000000000000
[42021.900294] R10: ffff94085f1aa000 R11: ffffffffc0775680 R12: ffffffff87ca2530
[42021.907355] R13: ffff940651602840 R14: ffff93c6cbbdbcb0 R15: ffff94085f1aa000
[42021.914418] FS: 00007fda1a3b9700(0000) GS:ffff94453fb80000(0000) knlGS:0000000000000000
[42021.922423] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[42021.928130] CR2: 0000000000000028 CR3: 00000042dcfb8003 CR4: 00000000003726f0
[42021.935194] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[42021.942257] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[42021.949324] Call Trace:
[42021.951756] <TASK>
[42021.953842] [<ffffffff86c58674>] ? show_regs+0x64/0x70
[42021.959030] [<ffffffff86c58468>] ? __die+0x78/0xc0
[42021.963874] [<ffffffff86c9ef75>] ? page_fault_oops+0x2b5/0x3b0
[42021.969749] [<ffffffff87674b92>] ? exc_page_fault+0x1a2/0x3c0
[42021.975549] [<ffffffff87801326>] ? asm_exc_page_fault+0x26/0x30
[42021.981517] [<ffffffffc0775680>] ? __pfx_show_hw_stats+0x10/0x10 [ib_core]
[42021.988482] [<ffffffffc077564e>] ? hw_stat_device_show+0x1e/0x40 [ib_core]
[42021.995438] [<ffffffff86ac7f8e>] dev_attr_show+0x1e/0x50
[42022.000803] [<ffffffff86a3eeb1>] sysfs_kf_seq_show+0x81/0xe0
[42022.006508] [<ffffffff86a11134>] seq_read_iter+0xf4/0x410
[42022.011954] [<ffffffff869f4b2e>] vfs_read+0x16e/0x2f0
[42022.017058] [<ffffffff869f50ee>] ksys_read+0x6e/0xe0
[42022.022073] [<ffffffff8766f1ca>] do_syscall_64+0x6a/0xa0
[42022.027441] [<ffffffff8780013b>] entry_SYSCALL_64_after_hwframe+0x78/0xe2
The problem can be reproduced using the following steps:
ip netns add foo
ip netns exec foo bash
cat /sys/class/infiniband/mlx4_0/hw_counters/*
The panic occurs because of casting the device pointer into an
ib_device pointer using container_of() in hw_stat_device_show() is
wrong and leads to a memory corruption.
However the real problem is that hw counters should never been exposed
outside of the non-init net namespace.
Fix this by saving the index of the corresponding attribute group
(it might be 1 or 2 depending on the presence of driver-specific
attributes) and zeroing the pointer to hw_counters group for compat
devices during the initialization.
With this fix applied hw_counters are not available in a non-init
net namespace:
find /sys/class/infiniband/mlx4_0/ -name hw_counters
/sys/class/infiniband/mlx4_0/ports/1/hw_counters
/sys/class/infiniband/mlx4_0/ports/2/hw_counters
/sys/class/infiniband/mlx4_0/hw_counters
ip netns add foo
ip netns exec foo bash
find /sys/class/infiniband/mlx4_0/ -name hw_counters
In the Linux kernel, the following vulnerability has been resolved:
RDMA/erdma: Prevent use-after-free in erdma_accept_newconn()
After the erdma_cep_put(new_cep) being called, new_cep will be freed,
and the following dereference will cause a UAF problem. Fix this issue.
In the Linux kernel, the following vulnerability has been resolved:
bpf: Fix array bounds error with may_goto
may_goto uses an additional 8 bytes on the stack, which causes the
interpreters[] array to go out of bounds when calculating index by
stack_size.
1. If a BPF program is rewritten, re-evaluate the stack size. For non-JIT
cases, reject loading directly.
2. For non-JIT cases, calculating interpreters[idx] may still cause
out-of-bounds array access, and just warn about it.
3. For jit_requested cases, the execution of bpf_func also needs to be
warned. So move the definition of function __bpf_prog_ret0_warn out of
the macro definition CONFIG_BPF_JIT_ALWAYS_ON.
In the Linux kernel, the following vulnerability has been resolved:
RDMA/mlx5: Fix mlx5_poll_one() cur_qp update flow
When cur_qp isn't NULL, in order to avoid fetching the QP from
the radix tree again we check if the next cqe QP is identical to
the one we already have.
The bug however is that we are checking if the QP is identical by
checking the QP number inside the CQE against the QP number inside the
mlx5_ib_qp, but that's wrong since the QP number from the CQE is from
FW so it should be matched against mlx5_core_qp which is our FW QP
number.
Otherwise we could use the wrong QP when handling a CQE which could
cause the kernel trace below.
This issue is mainly noticeable over QPs 0 & 1, since for now they are
the only QPs in our driver whereas the QP number inside mlx5_ib_qp
doesn't match the QP number inside mlx5_core_qp.
BUG: kernel NULL pointer dereference, address: 0000000000000012
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: Oops: 0000 [#1] SMP
CPU: 0 UID: 0 PID: 7927 Comm: kworker/u62:1 Not tainted 6.14.0-rc3+ #189
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
Workqueue: ib-comp-unb-wq ib_cq_poll_work [ib_core]
RIP: 0010:mlx5_ib_poll_cq+0x4c7/0xd90 [mlx5_ib]
Code: 03 00 00 8d 58 ff 21 cb 66 39 d3 74 39 48 c7 c7 3c 89 6e a0 0f b7 db e8 b7 d2 b3 e0 49 8b 86 60 03 00 00 48 c7 c7 4a 89 6e a0 <0f> b7 5c 98 02 e8 9f d2 b3 e0 41 0f b7 86 78 03 00 00 83 e8 01 21
RSP: 0018:ffff88810511bd60 EFLAGS: 00010046
RAX: 0000000000000010 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffff88885fa1b3c0 RDI: ffffffffa06e894a
RBP: 00000000000000b0 R08: 0000000000000000 R09: ffff88810511bc10
R10: 0000000000000001 R11: 0000000000000001 R12: ffff88810d593000
R13: ffff88810e579108 R14: ffff888105146000 R15: 00000000000000b0
FS: 0000000000000000(0000) GS:ffff88885fa00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000012 CR3: 00000001077e6001 CR4: 0000000000370eb0
Call Trace:
<TASK>
? __die+0x20/0x60
? page_fault_oops+0x150/0x3e0
? exc_page_fault+0x74/0x130
? asm_exc_page_fault+0x22/0x30
? mlx5_ib_poll_cq+0x4c7/0xd90 [mlx5_ib]
__ib_process_cq+0x5a/0x150 [ib_core]
ib_cq_poll_work+0x31/0x90 [ib_core]
process_one_work+0x169/0x320
worker_thread+0x288/0x3a0
? work_busy+0xb0/0xb0
kthread+0xd7/0x1f0
? kthreads_online_cpu+0x130/0x130
? kthreads_online_cpu+0x130/0x130
ret_from_fork+0x2d/0x50
? kthreads_online_cpu+0x130/0x130
ret_from_fork_asm+0x11/0x20
</TASK>
In the Linux kernel, the following vulnerability has been resolved:
w1: fix NULL pointer dereference in probe
The w1_uart_probe() function calls w1_uart_serdev_open() (which includes
devm_serdev_device_open()) before setting the client ops via
serdev_device_set_client_ops(). This ordering can trigger a NULL pointer
dereference in the serdev controller's receive_buf handler, as it assumes
serdev->ops is valid when SERPORT_ACTIVE is set.
This is similar to the issue fixed in commit 5e700b384ec1
("platform/chrome: cros_ec_uart: properly fix race condition") where
devm_serdev_device_open() was called before fully initializing the
device.
Fix the race by ensuring client ops are set before enabling the port via
w1_uart_serdev_open().
In the Linux kernel, the following vulnerability has been resolved:
vhost-scsi: Fix handling of multiple calls to vhost_scsi_set_endpoint
If vhost_scsi_set_endpoint is called multiple times without a
vhost_scsi_clear_endpoint between them, we can hit multiple bugs
found by Haoran Zhang:
1. Use-after-free when no tpgs are found:
This fixes a use after free that occurs when vhost_scsi_set_endpoint is
called more than once and calls after the first call do not find any
tpgs to add to the vs_tpg. When vhost_scsi_set_endpoint first finds
tpgs to add to the vs_tpg array match=true, so we will do:
vhost_vq_set_backend(vq, vs_tpg);
...
kfree(vs->vs_tpg);
vs->vs_tpg = vs_tpg;
If vhost_scsi_set_endpoint is called again and no tpgs are found
match=false so we skip the vhost_vq_set_backend call leaving the
pointer to the vs_tpg we then free via:
kfree(vs->vs_tpg);
vs->vs_tpg = vs_tpg;
If a scsi request is then sent we do:
vhost_scsi_handle_vq -> vhost_scsi_get_req -> vhost_vq_get_backend
which sees the vs_tpg we just did a kfree on.
2. Tpg dir removal hang:
This patch fixes an issue where we cannot remove a LIO/target layer
tpg (and structs above it like the target) dir due to the refcount
dropping to -1.
The problem is that if vhost_scsi_set_endpoint detects a tpg is already
in the vs->vs_tpg array or if the tpg has been removed so
target_depend_item fails, the undepend goto handler will do
target_undepend_item on all tpgs in the vs_tpg array dropping their
refcount to 0. At this time vs_tpg contains both the tpgs we have added
in the current vhost_scsi_set_endpoint call as well as tpgs we added in
previous calls which are also in vs->vs_tpg.
Later, when vhost_scsi_clear_endpoint runs it will do
target_undepend_item on all the tpgs in the vs->vs_tpg which will drop
their refcount to -1. Userspace will then not be able to remove the tpg
and will hang when it tries to do rmdir on the tpg dir.
3. Tpg leak:
This fixes a bug where we can leak tpgs and cause them to be
un-removable because the target name is overwritten when
vhost_scsi_set_endpoint is called multiple times but with different
target names.
The bug occurs if a user has called VHOST_SCSI_SET_ENDPOINT and setup
a vhost-scsi device to target/tpg mapping, then calls
VHOST_SCSI_SET_ENDPOINT again with a new target name that has tpgs we
haven't seen before (target1 has tpg1 but target2 has tpg2). When this
happens we don't teardown the old target tpg mapping and just overwrite
the target name and the vs->vs_tpg array. Later when we do
vhost_scsi_clear_endpoint, we are passed in either target1 or target2's
name and we will only match that target's tpgs when we loop over the
vs->vs_tpg. We will then return from the function without doing
target_undepend_item on the tpgs.
Because of all these bugs, it looks like being able to call
vhost_scsi_set_endpoint multiple times was never supported. The major
user, QEMU, already has checks to prevent this use case. So to fix the
issues, this patch prevents vhost_scsi_set_endpoint from being called
if it's already successfully added tpgs. To add, remove or change the
tpg config or target name, you must do a vhost_scsi_clear_endpoint
first.
In the Linux kernel, the following vulnerability has been resolved:
iio: backend: make sure to NULL terminate stack buffer
Make sure to NULL terminate the buffer in
iio_backend_debugfs_write_reg() before passing it to sscanf(). It is a
stack variable so we should not assume it will 0 initialized.
In the Linux kernel, the following vulnerability has been resolved:
fs/ntfs3: Fix a couple integer overflows on 32bit systems
On 32bit systems the "off + sizeof(struct NTFS_DE)" addition can
have an integer wrapping issue. Fix it by using size_add().
In the Linux kernel, the following vulnerability has been resolved:
fs/ntfs3: Prevent integer overflow in hdr_first_de()
The "de_off" and "used" variables come from the disk so they both need to
check. The problem is that on 32bit systems if they're both greater than
UINT_MAX - 16 then the check does work as intended because of an integer
overflow.
In the Linux kernel, the following vulnerability has been resolved:
ocfs2: validate l_tree_depth to avoid out-of-bounds access
The l_tree_depth field is 16-bit (__le16), but the actual maximum depth is
limited to OCFS2_MAX_PATH_DEPTH.
Add a check to prevent out-of-bounds access if l_tree_depth has an invalid
value, which may occur when reading from a corrupted mounted disk [1].
In the Linux kernel, the following vulnerability has been resolved:
staging: vchiq_arm: Fix possible NPR of keep-alive thread
In case vchiq_platform_conn_state_changed() is never called or fails before
driver removal, ka_thread won't be a valid pointer to a task_struct. So
do the necessary checks before calling kthread_stop to avoid a crash.
In the Linux kernel, the following vulnerability has been resolved:
Revert "smb: client: fix TCP timers deadlock after rmmod"
This reverts commit e9f2517a3e18a54a3943c098d2226b245d488801.
Commit e9f2517a3e18 ("smb: client: fix TCP timers deadlock after
rmmod") is intended to fix a null-ptr-deref in LOCKDEP, which is
mentioned as CVE-2024-54680, but is actually did not fix anything;
The issue can be reproduced on top of it. [0]
Also, it reverted the change by commit ef7134c7fc48 ("smb: client:
Fix use-after-free of network namespace.") and introduced a real
issue by reviving the kernel TCP socket.
When a reconnect happens for a CIFS connection, the socket state
transitions to FIN_WAIT_1. Then, inet_csk_clear_xmit_timers_sync()
in tcp_close() stops all timers for the socket.
If an incoming FIN packet is lost, the socket will stay at FIN_WAIT_1
forever, and such sockets could be leaked up to net.ipv4.tcp_max_orphans.
Usually, FIN can be retransmitted by the peer, but if the peer aborts
the connection, the issue comes into reality.
I warned about this privately by pointing out the exact report [1],
but the bogus fix was finally merged.
So, we should not stop the timers to finally kill the connection on
our side in that case, meaning we must not use a kernel socket for
TCP whose sk->sk_net_refcnt is 0.
The kernel socket does not have a reference to its netns to make it
possible to tear down netns without cleaning up every resource in it.
For example, tunnel devices use a UDP socket internally, but we can
destroy netns without removing such devices and let it complete
during exit. Otherwise, netns would be leaked when the last application
died.
However, this is problematic for TCP sockets because TCP has timers to
close the connection gracefully even after the socket is close()d. The
lifetime of the socket and its netns is different from the lifetime of
the underlying connection.
If the socket user does not maintain the netns lifetime, the timer could
be fired after the socket is close()d and its netns is freed up, resulting
in use-after-free.
Actually, we have seen so many similar issues and converted such sockets
to have a reference to netns.
That's why I converted the CIFS client socket to have a reference to
netns (sk->sk_net_refcnt == 1), which is somehow mentioned as out-of-scope
of CIFS and technically wrong in e9f2517a3e18, but **is in-scope and right
fix**.
Regarding the LOCKDEP issue, we can prevent the module unload by
bumping the module refcount when switching the LOCKDDEP key in
sock_lock_init_class_and_name(). [2]
For a while, let's revert the bogus fix.
Note that now we can use sk_net_refcnt_upgrade() for the socket
conversion, but I'll do so later separately to make backport easy.
In the Linux kernel, the following vulnerability has been resolved:
exfat: fix missing shutdown check
xfstests generic/730 test failed because after deleting the device
that still had dirty data, the file could still be read without
returning an error. The reason is the missing shutdown check in
->read_iter.
I also noticed that shutdown checks were missing from ->write_iter,
->splice_read, and ->mmap. This commit adds shutdown checks to all
of them.
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: fix r_count dec/increment mismatch
r_count is only increased when there is an oplock break wait,
so r_count inc/decrement are not paired. This can cause r_count
to become negative, which can lead to a problem where the ksmbd
thread does not terminate.
In the Linux kernel, the following vulnerability has been resolved:
spufs: fix a leak on spufs_new_file() failure
It's called from spufs_fill_dir(), and caller of that will do
spufs_rmdir() in case of failure. That does remove everything
we'd managed to create, but... the problem dentry is still
negative. IOW, it needs to be explicitly dropped.
In the Linux kernel, the following vulnerability has been resolved:
spufs: fix gang directory lifetimes
prior to "[POWERPC] spufs: Fix gang destroy leaks" we used to have
a problem with gang lifetimes - creation of a gang returns opened
gang directory, which normally gets removed when that gets closed,
but if somebody has created a context belonging to that gang and
kept it alive until the gang got closed, removal failed and we
ended up with a leak.
Unfortunately, it had been fixed the wrong way. Dentry of gang
directory was no longer pinned, and rmdir on close was gone.
One problem was that failure of open kept calling simple_rmdir()
as cleanup, which meant an unbalanced dput(). Another bug was
in the success case - gang creation incremented link count on
root directory, but that was no longer undone when gang got
destroyed.
Fix consists of
* reverting the commit in question
* adding a counter to gang, protected by ->i_rwsem
of gang directory inode.
* having it set to 1 at creation time, dropped
in both spufs_dir_close() and spufs_gang_close() and bumped
in spufs_create_context(), provided that it's not 0.
* using simple_recursive_removal() to take the gang
directory out when counter reaches zero.
In the Linux kernel, the following vulnerability has been resolved:
spufs: fix a leak in spufs_create_context()
Leak fixes back in 2008 missed one case - if we are trying to set affinity
and spufs_mkdir() fails, we need to drop the reference to neighbor.
In the Linux kernel, the following vulnerability has been resolved:
ublk: make sure ubq->canceling is set when queue is frozen
Now ublk driver depends on `ubq->canceling` for deciding if the request
can be dispatched via uring_cmd & io_uring_cmd_complete_in_task().
Once ubq->canceling is set, the uring_cmd can be done via ublk_cancel_cmd()
and io_uring_cmd_done().
So set ubq->canceling when queue is frozen, this way makes sure that the
flag can be observed from ublk_queue_rq() reliably, and avoids
use-after-free on uring_cmd.
In the Linux kernel, the following vulnerability has been resolved:
spi: cadence: Fix out-of-bounds array access in cdns_mrvl_xspi_setup_clock()
If requested_clk > 128, cdns_mrvl_xspi_setup_clock() iterates over the
entire cdns_mrvl_xspi_clk_div_list array without breaking out early,
causing 'i' to go beyond the array bounds.
Fix that by stopping the loop when it gets to the last entry, clamping
the clock to the minimum 6.25 MHz.
Fixes the following warning with an UBSAN kernel:
vmlinux.o: warning: objtool: cdns_mrvl_xspi_setup_clock: unexpected end of section .text.cdns_mrvl_xspi_setup_clock
In the Linux kernel, the following vulnerability has been resolved:
ASoC: imx-card: Add NULL check in imx_card_probe()
devm_kasprintf() returns NULL when memory allocation fails. Currently,
imx_card_probe() does not check for this case, which results in a NULL
pointer dereference.
Add NULL check after devm_kasprintf() to prevent this issue.
In the Linux kernel, the following vulnerability has been resolved:
idpf: fix adapter NULL pointer dereference on reboot
With SRIOV enabled, idpf ends up calling into idpf_remove() twice.
First via idpf_shutdown() and then again when idpf_remove() calls into
sriov_disable(), because the VF devices use the idpf driver, hence the
same remove routine. When that happens, it is possible for the adapter
to be NULL from the first call to idpf_remove(), leading to a NULL
pointer dereference.
echo 1 > /sys/class/net/<netif>/device/sriov_numvfs
reboot
BUG: kernel NULL pointer dereference, address: 0000000000000020
...
RIP: 0010:idpf_remove+0x22/0x1f0 [idpf]
...
? idpf_remove+0x22/0x1f0 [idpf]
? idpf_remove+0x1e4/0x1f0 [idpf]
pci_device_remove+0x3f/0xb0
device_release_driver_internal+0x19f/0x200
pci_stop_bus_device+0x6d/0x90
pci_stop_and_remove_bus_device+0x12/0x20
pci_iov_remove_virtfn+0xbe/0x120
sriov_disable+0x34/0xe0
idpf_sriov_configure+0x58/0x140 [idpf]
idpf_remove+0x1b9/0x1f0 [idpf]
idpf_shutdown+0x12/0x30 [idpf]
pci_device_shutdown+0x35/0x60
device_shutdown+0x156/0x200
...
Replace the direct idpf_remove() call in idpf_shutdown() with
idpf_vc_core_deinit() and idpf_deinit_dflt_mbx(), which perform
the bulk of the cleanup, such as stopping the init task, freeing IRQs,
destroying the vports and freeing the mailbox. This avoids the calls to
sriov_disable() in addition to a small netdev cleanup, and destroying
workqueues, which don't seem to be required on shutdown.
In the Linux kernel, the following vulnerability has been resolved:
netfilter: nf_tables: don't unregister hook when table is dormant
When nf_tables_updchain encounters an error, hook registration needs to
be rolled back.
This should only be done if the hook has been registered, which won't
happen when the table is flagged as dormant (inactive).
Just move the assignment into the registration block.
In the Linux kernel, the following vulnerability has been resolved:
netlabel: Fix NULL pointer exception caused by CALIPSO on IPv4 sockets
When calling netlbl_conn_setattr(), addr->sa_family is used
to determine the function behavior. If sk is an IPv4 socket,
but the connect function is called with an IPv6 address,
the function calipso_sock_setattr() is triggered.
Inside this function, the following code is executed:
sk_fullsock(__sk) ? inet_sk(__sk)->pinet6 : NULL;
Since sk is an IPv4 socket, pinet6 is NULL, leading to a
null pointer dereference.
This patch fixes the issue by checking if inet6_sk(sk)
returns a NULL pointer before accessing pinet6.
In the Linux kernel, the following vulnerability has been resolved:
sctp: add mutual exclusion in proc_sctp_do_udp_port()
We must serialize calls to sctp_udp_sock_stop() and sctp_udp_sock_start()
or risk a crash as syzbot reported:
Oops: general protection fault, probably for non-canonical address 0xdffffc000000000d: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000068-0x000000000000006f]
CPU: 1 UID: 0 PID: 6551 Comm: syz.1.44 Not tainted 6.14.0-syzkaller-g7f2ff7b62617 #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:kernel_sock_shutdown+0x47/0x70 net/socket.c:3653
Call Trace:
<TASK>
udp_tunnel_sock_release+0x68/0x80 net/ipv4/udp_tunnel_core.c:181
sctp_udp_sock_stop+0x71/0x160 net/sctp/protocol.c:930
proc_sctp_do_udp_port+0x264/0x450 net/sctp/sysctl.c:553
proc_sys_call_handler+0x3d0/0x5b0 fs/proc/proc_sysctl.c:601
iter_file_splice_write+0x91c/0x1150 fs/splice.c:738
do_splice_from fs/splice.c:935 [inline]
direct_splice_actor+0x18f/0x6c0 fs/splice.c:1158
splice_direct_to_actor+0x342/0xa30 fs/splice.c:1102
do_splice_direct_actor fs/splice.c:1201 [inline]
do_splice_direct+0x174/0x240 fs/splice.c:1227
do_sendfile+0xafd/0xe50 fs/read_write.c:1368
__do_sys_sendfile64 fs/read_write.c:1429 [inline]
__se_sys_sendfile64 fs/read_write.c:1415 [inline]
__x64_sys_sendfile64+0x1d8/0x220 fs/read_write.c:1415
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
In the Linux kernel, the following vulnerability has been resolved:
net: mvpp2: Prevent parser TCAM memory corruption
Protect the parser TCAM/SRAM memory, and the cached (shadow) SRAM
information, from concurrent modifications.
Both the TCAM and SRAM tables are indirectly accessed by configuring
an index register that selects the row to read or write to. This means
that operations must be atomic in order to, e.g., avoid spreading
writes across multiple rows. Since the shadow SRAM array is used to
find free rows in the hardware table, it must also be protected in
order to avoid TOCTOU errors where multiple cores allocate the same
row.
This issue was detected in a situation where `mvpp2_set_rx_mode()` ran
concurrently on two CPUs. In this particular case the
MVPP2_PE_MAC_UC_PROMISCUOUS entry was corrupted, causing the
classifier unit to drop all incoming unicast - indicated by the
`rx_classifier_drops` counter.
In the Linux kernel, the following vulnerability has been resolved:
udp: Fix multiple wraparounds of sk->sk_rmem_alloc.
__udp_enqueue_schedule_skb() has the following condition:
if (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf)
goto drop;
sk->sk_rcvbuf is initialised by net.core.rmem_default and later can
be configured by SO_RCVBUF, which is limited by net.core.rmem_max,
or SO_RCVBUFFORCE.
If we set INT_MAX to sk->sk_rcvbuf, the condition is always false
as sk->sk_rmem_alloc is also signed int.
Then, the size of the incoming skb is added to sk->sk_rmem_alloc
unconditionally.
This results in integer overflow (possibly multiple times) on
sk->sk_rmem_alloc and allows a single socket to have skb up to
net.core.udp_mem[1].
For example, if we set a large value to udp_mem[1] and INT_MAX to
sk->sk_rcvbuf and flood packets to the socket, we can see multiple
overflows:
# cat /proc/net/sockstat | grep UDP:
UDP: inuse 3 mem 7956736 <-- (7956736 << 12) bytes > INT_MAX * 15
^- PAGE_SHIFT
# ss -uam
State Recv-Q ...
UNCONN -1757018048 ... <-- flipping the sign repeatedly
skmem:(r2537949248,rb2147483646,t0,tb212992,f1984,w0,o0,bl0,d0)
Previously, we had a boundary check for INT_MAX, which was removed by
commit 6a1f12dd85a8 ("udp: relax atomic operation on sk->sk_rmem_alloc").
A complete fix would be to revert it and cap the right operand by
INT_MAX:
rmem = atomic_add_return(size, &sk->sk_rmem_alloc);
if (rmem > min(size + (unsigned int)sk->sk_rcvbuf, INT_MAX))
goto uncharge_drop;
but we do not want to add the expensive atomic_add_return() back just
for the corner case.
Casting rmem to unsigned int prevents multiple wraparounds, but we still
allow a single wraparound.
# cat /proc/net/sockstat | grep UDP:
UDP: inuse 3 mem 524288 <-- (INT_MAX + 1) >> 12
# ss -uam
State Recv-Q ...
UNCONN -2147482816 ... <-- INT_MAX + 831 bytes
skmem:(r2147484480,rb2147483646,t0,tb212992,f3264,w0,o0,bl0,d14468947)
So, let's define rmem and rcvbuf as unsigned int and check skb->truesize
only when rcvbuf is large enough to lower the overflow possibility.
Note that we still have a small chance to see overflow if multiple skbs
to the same socket are processed on different core at the same time and
each size does not exceed the limit but the total size does.
Note also that we must ignore skb->truesize for a small buffer as
explained in commit 363dc73acacb ("udp: be less conservative with
sock rmem accounting").
In the Linux kernel, the following vulnerability has been resolved:
udp: Fix memory accounting leak.
Matt Dowling reported a weird UDP memory usage issue.
Under normal operation, the UDP memory usage reported in /proc/net/sockstat
remains close to zero. However, it occasionally spiked to 524,288 pages
and never dropped. Moreover, the value doubled when the application was
terminated. Finally, it caused intermittent packet drops.
We can reproduce the issue with the script below [0]:
1. /proc/net/sockstat reports 0 pages
# cat /proc/net/sockstat | grep UDP:
UDP: inuse 1 mem 0
2. Run the script till the report reaches 524,288
# python3 test.py & sleep 5
# cat /proc/net/sockstat | grep UDP:
UDP: inuse 3 mem 524288 <-- (INT_MAX + 1) >> PAGE_SHIFT
3. Kill the socket and confirm the number never drops
# pkill python3 && sleep 5
# cat /proc/net/sockstat | grep UDP:
UDP: inuse 1 mem 524288
4. (necessary since v6.0) Trigger proto_memory_pcpu_drain()
# python3 test.py & sleep 1 && pkill python3
5. The number doubles
# cat /proc/net/sockstat | grep UDP:
UDP: inuse 1 mem 1048577
The application set INT_MAX to SO_RCVBUF, which triggered an integer
overflow in udp_rmem_release().
When a socket is close()d, udp_destruct_common() purges its receive
queue and sums up skb->truesize in the queue. This total is calculated
and stored in a local unsigned integer variable.
The total size is then passed to udp_rmem_release() to adjust memory
accounting. However, because the function takes a signed integer
argument, the total size can wrap around, causing an overflow.
Then, the released amount is calculated as follows:
1) Add size to sk->sk_forward_alloc.
2) Round down sk->sk_forward_alloc to the nearest lower multiple of
PAGE_SIZE and assign it to amount.
3) Subtract amount from sk->sk_forward_alloc.
4) Pass amount >> PAGE_SHIFT to __sk_mem_reduce_allocated().
When the issue occurred, the total in udp_destruct_common() was 2147484480
(INT_MAX + 833), which was cast to -2147482816 in udp_rmem_release().
At 1) sk->sk_forward_alloc is changed from 3264 to -2147479552, and
2) sets -2147479552 to amount. 3) reverts the wraparound, so we don't
see a warning in inet_sock_destruct(). However, udp_memory_allocated
ends up doubling at 4).
Since commit 3cd3399dd7a8 ("net: implement per-cpu reserves for
memory_allocated"), memory usage no longer doubles immediately after
a socket is close()d because __sk_mem_reduce_allocated() caches the
amount in udp_memory_per_cpu_fw_alloc. However, the next time a UDP
socket receives a packet, the subtraction takes effect, causing UDP
memory usage to double.
This issue makes further memory allocation fail once the socket's
sk->sk_rmem_alloc exceeds net.ipv4.udp_rmem_min, resulting in packet
drops.
To prevent this issue, let's use unsigned int for the calculation and
call sk_forward_alloc_add() only once for the small delta.
Note that first_packet_length() also potentially has the same problem.
[0]:
from socket import *
SO_RCVBUFFORCE = 33
INT_MAX = (2 ** 31) - 1
s = socket(AF_INET, SOCK_DGRAM)
s.bind(('', 0))
s.setsockopt(SOL_SOCKET, SO_RCVBUFFORCE, INT_MAX)
c = socket(AF_INET, SOCK_DGRAM)
c.connect(s.getsockname())
data = b'a' * 100
while True:
c.send(data)