| CVE |
Vendors |
Products |
Updated |
CVSS v3.1 |
| In the Linux kernel, the following vulnerability has been resolved:
caif: fix integer underflow in cffrml_receive()
The cffrml_receive() function extracts a length field from the packet
header and, when FCS is disabled, subtracts 2 from this length without
validating that len >= 2.
If an attacker sends a malicious packet with a length field of 0 or 1
to an interface with FCS disabled, the subtraction causes an integer
underflow.
This can lead to memory exhaustion and kernel instability, potential
information disclosure if padding contains uninitialized kernel memory.
Fix this by validating that len >= 2 before performing the subtraction. |
| In the Linux kernel, the following vulnerability has been resolved:
mlxsw: spectrum_mr: Fix use-after-free when updating multicast route stats
Cited commit added a dedicated mutex (instead of RTNL) to protect the
multicast route list, so that it will not change while the driver
periodically traverses it in order to update the kernel about multicast
route stats that were queried from the device.
One instance of list entry deletion (during route replace) was missed
and it can result in a use-after-free [1].
Fix by acquiring the mutex before deleting the entry from the list and
releasing it afterwards.
[1]
BUG: KASAN: slab-use-after-free in mlxsw_sp_mr_stats_update+0x4a5/0x540 drivers/net/ethernet/mellanox/mlxsw/spectrum_mr.c:1006 [mlxsw_spectrum]
Read of size 8 at addr ffff8881523c2fa8 by task kworker/2:5/22043
CPU: 2 UID: 0 PID: 22043 Comm: kworker/2:5 Not tainted 6.18.0-rc1-custom-g1a3d6d7cd014 #1 PREEMPT(full)
Hardware name: Mellanox Technologies Ltd. MSN2010/SA002610, BIOS 5.6.5 08/24/2017
Workqueue: mlxsw_core mlxsw_sp_mr_stats_update [mlxsw_spectrum]
Call Trace:
<TASK>
dump_stack_lvl+0xba/0x110
print_report+0x174/0x4f5
kasan_report+0xdf/0x110
mlxsw_sp_mr_stats_update+0x4a5/0x540 drivers/net/ethernet/mellanox/mlxsw/spectrum_mr.c:1006 [mlxsw_spectrum]
process_one_work+0x9cc/0x18e0
worker_thread+0x5df/0xe40
kthread+0x3b8/0x730
ret_from_fork+0x3e9/0x560
ret_from_fork_asm+0x1a/0x30
</TASK>
Allocated by task 29933:
kasan_save_stack+0x30/0x50
kasan_save_track+0x14/0x30
__kasan_kmalloc+0x8f/0xa0
mlxsw_sp_mr_route_add+0xd8/0x4770 [mlxsw_spectrum]
mlxsw_sp_router_fibmr_event_work+0x371/0xad0 drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c:7965 [mlxsw_spectrum]
process_one_work+0x9cc/0x18e0
worker_thread+0x5df/0xe40
kthread+0x3b8/0x730
ret_from_fork+0x3e9/0x560
ret_from_fork_asm+0x1a/0x30
Freed by task 29933:
kasan_save_stack+0x30/0x50
kasan_save_track+0x14/0x30
__kasan_save_free_info+0x3b/0x70
__kasan_slab_free+0x43/0x70
kfree+0x14e/0x700
mlxsw_sp_mr_route_add+0x2dea/0x4770 drivers/net/ethernet/mellanox/mlxsw/spectrum_mr.c:444 [mlxsw_spectrum]
mlxsw_sp_router_fibmr_event_work+0x371/0xad0 drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c:7965 [mlxsw_spectrum]
process_one_work+0x9cc/0x18e0
worker_thread+0x5df/0xe40
kthread+0x3b8/0x730
ret_from_fork+0x3e9/0x560
ret_from_fork_asm+0x1a/0x30 |
| In the Linux kernel, the following vulnerability has been resolved:
block: fix race between wbt_enable_default and IO submission
When wbt_enable_default() is moved out of queue freezing in elevator_change(),
it can cause the wbt inflight counter to become negative (-1), leading to hung
tasks in the writeback path. Tasks get stuck in wbt_wait() because the counter
is in an inconsistent state.
The issue occurs because wbt_enable_default() could race with IO submission,
allowing the counter to be decremented before proper initialization. This manifests
as:
rq_wait[0]:
inflight: -1
has_waiters: True
rwb_enabled() checks the state, which can be updated exactly between wbt_wait()
(rq_qos_throttle()) and wbt_track()(rq_qos_track()), then the inflight counter
will become negative.
And results in hung task warnings like:
task:kworker/u24:39 state:D stack:0 pid:14767
Call Trace:
rq_qos_wait+0xb4/0x150
wbt_wait+0xa9/0x100
__rq_qos_throttle+0x24/0x40
blk_mq_submit_bio+0x672/0x7b0
...
Fix this by:
1. Splitting wbt_enable_default() into:
- __wbt_enable_default(): Returns true if wbt_init() should be called
- wbt_enable_default(): Wrapper for existing callers (no init)
- wbt_init_enable_default(): New function that checks and inits WBT
2. Using wbt_init_enable_default() in blk_register_queue() to ensure
proper initialization during queue registration
3. Move wbt_init() out of wbt_enable_default() which is only for enabling
disabled wbt from bfq and iocost, and wbt_init() isn't needed. Then the
original lock warning can be avoided.
4. Removing the ELEVATOR_FLAG_ENABLE_WBT_ON_EXIT flag and its handling
code since it's no longer needed
This ensures WBT is properly initialized before any IO can be submitted,
preventing the counter from going negative. |
| In the Linux kernel, the following vulnerability has been resolved:
ksmbd: vfs: fix race on m_flags in vfs_cache
ksmbd maintains delete-on-close and pending-delete state in
ksmbd_inode->m_flags. In vfs_cache.c this field is accessed under
inconsistent locking: some paths read and modify m_flags under
ci->m_lock while others do so without taking the lock at all.
Examples:
- ksmbd_query_inode_status() and __ksmbd_inode_close() use
ci->m_lock when checking or updating m_flags.
- ksmbd_inode_pending_delete(), ksmbd_set_inode_pending_delete(),
ksmbd_clear_inode_pending_delete() and ksmbd_fd_set_delete_on_close()
used to read and modify m_flags without ci->m_lock.
This creates a potential data race on m_flags when multiple threads
open, close and delete the same file concurrently. In the worst case
delete-on-close and pending-delete bits can be lost or observed in an
inconsistent state, leading to confusing delete semantics (files that
stay on disk after delete-on-close, or files that disappear while still
in use).
Fix it by:
- Making ksmbd_query_inode_status() look at m_flags under ci->m_lock
after dropping inode_hash_lock.
- Adding ci->m_lock protection to all helpers that read or modify
m_flags (ksmbd_inode_pending_delete(), ksmbd_set_inode_pending_delete(),
ksmbd_clear_inode_pending_delete(), ksmbd_fd_set_delete_on_close()).
- Keeping the existing ci->m_lock protection in __ksmbd_inode_close(),
and moving the actual unlink/xattr removal outside the lock.
This unifies the locking around m_flags and removes the data race while
preserving the existing delete-on-close behaviour. |
| In the Linux kernel, the following vulnerability has been resolved:
svcrdma: use rc_pageoff for memcpy byte offset
svc_rdma_copy_inline_range added rc_curpage (page index) to the page
base instead of the byte offset rc_pageoff. Use rc_pageoff so copies
land within the current page.
Found by ZeroPath (https://zeropath.com) |
| In the Linux kernel, the following vulnerability has been resolved:
drm/xe/guc: Synchronize Dead CT worker with unbind
Cancel and wait for any Dead CT worker to complete before continuing
with device unbinding. Else the worker will end up using resources freed
by the undind operation.
(cherry picked from commit 492671339114e376aaa38626d637a2751cdef263) |
| In the Linux kernel, the following vulnerability has been resolved:
fuse: fix readahead reclaim deadlock
Commit e26ee4efbc79 ("fuse: allocate ff->release_args only if release is
needed") skips allocating ff->release_args if the server does not
implement open. However in doing so, fuse_prepare_release() now skips
grabbing the reference on the inode, which makes it possible for an
inode to be evicted from the dcache while there are inflight readahead
requests. This causes a deadlock if the server triggers reclaim while
servicing the readahead request and reclaim attempts to evict the inode
of the file being read ahead. Since the folio is locked during
readahead, when reclaim evicts the fuse inode and fuse_evict_inode()
attempts to remove all folios associated with the inode from the page
cache (truncate_inode_pages_range()), reclaim will block forever waiting
for the lock since readahead cannot relinquish the lock because it is
itself blocked in reclaim:
>>> stack_trace(1504735)
folio_wait_bit_common (mm/filemap.c:1308:4)
folio_lock (./include/linux/pagemap.h:1052:3)
truncate_inode_pages_range (mm/truncate.c:336:10)
fuse_evict_inode (fs/fuse/inode.c:161:2)
evict (fs/inode.c:704:3)
dentry_unlink_inode (fs/dcache.c:412:3)
__dentry_kill (fs/dcache.c:615:3)
shrink_kill (fs/dcache.c:1060:12)
shrink_dentry_list (fs/dcache.c:1087:3)
prune_dcache_sb (fs/dcache.c:1168:2)
super_cache_scan (fs/super.c:221:10)
do_shrink_slab (mm/shrinker.c:435:9)
shrink_slab (mm/shrinker.c:626:10)
shrink_node (mm/vmscan.c:5951:2)
shrink_zones (mm/vmscan.c:6195:3)
do_try_to_free_pages (mm/vmscan.c:6257:3)
do_swap_page (mm/memory.c:4136:11)
handle_pte_fault (mm/memory.c:5562:10)
handle_mm_fault (mm/memory.c:5870:9)
do_user_addr_fault (arch/x86/mm/fault.c:1338:10)
handle_page_fault (arch/x86/mm/fault.c:1481:3)
exc_page_fault (arch/x86/mm/fault.c:1539:2)
asm_exc_page_fault+0x22/0x27
Fix this deadlock by allocating ff->release_args and grabbing the
reference on the inode when preparing the file for release even if the
server does not implement open. The inode reference will be dropped when
the last reference on the fuse file is dropped (see fuse_file_put() ->
fuse_release_end()). |
| In the Linux kernel, the following vulnerability has been resolved:
Input: alps - fix use-after-free bugs caused by dev3_register_work
The dev3_register_work delayed work item is initialized within
alps_reconnect() and scheduled upon receipt of the first bare
PS/2 packet from an external PS/2 device connected to the ALPS
touchpad. During device detachment, the original implementation
calls flush_workqueue() in psmouse_disconnect() to ensure
completion of dev3_register_work. However, the flush_workqueue()
in psmouse_disconnect() only blocks and waits for work items that
were already queued to the workqueue prior to its invocation. Any
work items submitted after flush_workqueue() is called are not
included in the set of tasks that the flush operation awaits.
This means that after flush_workqueue() has finished executing,
the dev3_register_work could still be scheduled. Although the
psmouse state is set to PSMOUSE_CMD_MODE in psmouse_disconnect(),
the scheduling of dev3_register_work remains unaffected.
The race condition can occur as follows:
CPU 0 (cleanup path) | CPU 1 (delayed work)
psmouse_disconnect() |
psmouse_set_state() |
flush_workqueue() | alps_report_bare_ps2_packet()
alps_disconnect() | psmouse_queue_work()
kfree(priv); // FREE | alps_register_bare_ps2_mouse()
| priv = container_of(work...); // USE
| priv->dev3 // USE
Add disable_delayed_work_sync() in alps_disconnect() to ensure
that dev3_register_work is properly canceled and prevented from
executing after the alps_data structure has been deallocated.
This bug is identified by static analysis. |
| In the Linux kernel, the following vulnerability has been resolved:
scsi: mpi3mr: Fix an issue found by KASAN
Write only correct size (32 instead of 64 bytes). |
| In the Linux kernel, the following vulnerability has been resolved:
Input: imx_sc_key - fix memory corruption on unload
This is supposed to be "priv" but we accidentally pass "&priv" which is
an address in the stack and so it will lead to memory corruption when
the imx_sc_key_action() function is called. Remove the &. |
| In the Linux kernel, the following vulnerability has been resolved:
net: hns3: using the num_tqps in the vf driver to apply for resources
Currently, hdev->htqp is allocated using hdev->num_tqps, and kinfo->tqp
is allocated using kinfo->num_tqps. However, kinfo->num_tqps is set to
min(new_tqps, hdev->num_tqps); Therefore, kinfo->num_tqps may be smaller
than hdev->num_tqps, which causes some hdev->htqp[i] to remain
uninitialized in hclgevf_knic_setup().
Thus, this patch allocates hdev->htqp and kinfo->tqp using hdev->num_tqps,
ensuring that the lengths of hdev->htqp and kinfo->tqp are consistent
and that all elements are properly initialized. |
| In the Linux kernel, the following vulnerability has been resolved:
net/mlx5: Devcom, fix error flow in mlx5_devcom_register_device
In case devcom allocation is failed, mlx5 is always freeing the priv.
However, this priv might have been allocated by a different thread,
and freeing it might lead to use-after-free bugs.
Fix it by freeing the priv only in case it was allocated by the
running thread. |
| In the Linux kernel, the following vulnerability has been resolved:
net/sched: ets: Always remove class from active list before deleting in ets_qdisc_change
zdi-disclosures@trendmicro.com says:
The vulnerability is a race condition between `ets_qdisc_dequeue` and
`ets_qdisc_change`. It leads to UAF on `struct Qdisc` object.
Attacker requires the capability to create new user and network namespace
in order to trigger the bug.
See my additional commentary at the end of the analysis.
Analysis:
static int ets_qdisc_change(struct Qdisc *sch, struct nlattr *opt,
struct netlink_ext_ack *extack)
{
...
// (1) this lock is preventing .change handler (`ets_qdisc_change`)
//to race with .dequeue handler (`ets_qdisc_dequeue`)
sch_tree_lock(sch);
for (i = nbands; i < oldbands; i++) {
if (i >= q->nstrict && q->classes[i].qdisc->q.qlen)
list_del_init(&q->classes[i].alist);
qdisc_purge_queue(q->classes[i].qdisc);
}
WRITE_ONCE(q->nbands, nbands);
for (i = nstrict; i < q->nstrict; i++) {
if (q->classes[i].qdisc->q.qlen) {
// (2) the class is added to the q->active
list_add_tail(&q->classes[i].alist, &q->active);
q->classes[i].deficit = quanta[i];
}
}
WRITE_ONCE(q->nstrict, nstrict);
memcpy(q->prio2band, priomap, sizeof(priomap));
for (i = 0; i < q->nbands; i++)
WRITE_ONCE(q->classes[i].quantum, quanta[i]);
for (i = oldbands; i < q->nbands; i++) {
q->classes[i].qdisc = queues[i];
if (q->classes[i].qdisc != &noop_qdisc)
qdisc_hash_add(q->classes[i].qdisc, true);
}
// (3) the qdisc is unlocked, now dequeue can be called in parallel
// to the rest of .change handler
sch_tree_unlock(sch);
ets_offload_change(sch);
for (i = q->nbands; i < oldbands; i++) {
// (4) we're reducing the refcount for our class's qdisc and
// freeing it
qdisc_put(q->classes[i].qdisc);
// (5) If we call .dequeue between (4) and (5), we will have
// a strong UAF and we can control RIP
q->classes[i].qdisc = NULL;
WRITE_ONCE(q->classes[i].quantum, 0);
q->classes[i].deficit = 0;
gnet_stats_basic_sync_init(&q->classes[i].bstats);
memset(&q->classes[i].qstats, 0, sizeof(q->classes[i].qstats));
}
return 0;
}
Comment:
This happens because some of the classes have their qdiscs assigned to
NULL, but remain in the active list. This commit fixes this issue by always
removing the class from the active list before deleting and freeing its
associated qdisc
Reproducer Steps
(trimmed version of what was sent by zdi-disclosures@trendmicro.com)
```
DEV="${DEV:-lo}"
ROOT_HANDLE="${ROOT_HANDLE:-1:}"
BAND2_HANDLE="${BAND2_HANDLE:-20:}" # child under 1:2
PING_BYTES="${PING_BYTES:-48}"
PING_COUNT="${PING_COUNT:-200000}"
PING_DST="${PING_DST:-127.0.0.1}"
SLOW_TBF_RATE="${SLOW_TBF_RATE:-8bit}"
SLOW_TBF_BURST="${SLOW_TBF_BURST:-100b}"
SLOW_TBF_LAT="${SLOW_TBF_LAT:-1s}"
cleanup() {
tc qdisc del dev "$DEV" root 2>/dev/null
}
trap cleanup EXIT
ip link set "$DEV" up
tc qdisc del dev "$DEV" root 2>/dev/null || true
tc qdisc add dev "$DEV" root handle "$ROOT_HANDLE" ets bands 2 strict 2
tc qdisc add dev "$DEV" parent 1:2 handle "$BAND2_HANDLE" \
tbf rate "$SLOW_TBF_RATE" burst "$SLOW_TBF_BURST" latency "$SLOW_TBF_LAT"
tc filter add dev "$DEV" parent 1: protocol all prio 1 u32 match u32 0 0 flowid 1:2
tc -s qdisc ls dev $DEV
ping -I "$DEV" -f -c "$PING_COUNT" -s "$PING_BYTES" -W 0.001 "$PING_DST" \
>/dev/null 2>&1 &
tc qdisc change dev "$DEV" root handle "$ROOT_HANDLE" ets bands 2 strict 0
tc qdisc change dev "$DEV" root handle "$ROOT_HANDLE" ets bands 2 strict 2
tc -s qdisc ls dev $DEV
tc qdisc del dev "$DEV" parent
---truncated--- |
| In the Linux kernel, the following vulnerability has been resolved:
ntfs: set dummy blocksize to read boot_block when mounting
When mounting, sb->s_blocksize is used to read the boot_block without
being defined or validated. Set a dummy blocksize before attempting to
read the boot_block.
The issue can be triggered with the following syz reproducer:
mkdirat(0xffffffffffffff9c, &(0x7f0000000080)='./file1\x00', 0x0)
r4 = openat$nullb(0xffffffffffffff9c, &(0x7f0000000040), 0x121403, 0x0)
ioctl$FS_IOC_SETFLAGS(r4, 0x40081271, &(0x7f0000000980)=0x4000)
mount(&(0x7f0000000140)=@nullb, &(0x7f0000000040)='./cgroup\x00',
&(0x7f0000000000)='ntfs3\x00', 0x2208004, 0x0)
syz_clone(0x88200200, 0x0, 0x0, 0x0, 0x0, 0x0)
Here, the ioctl sets the bdev block size to 16384. During mount,
get_tree_bdev_flags() calls sb_set_blocksize(sb, block_size(bdev)),
but since block_size(bdev) > PAGE_SIZE, sb_set_blocksize() leaves
sb->s_blocksize at zero.
Later, ntfs_init_from_boot() attempts to read the boot_block while
sb->s_blocksize is still zero, which triggers the bug.
[almaz.alexandrovich@paragon-software.com: changed comment style, added
return value handling] |
| In the Linux kernel, the following vulnerability has been resolved:
net: use dst_dev_rcu() in sk_setup_caps()
Use RCU to protect accesses to dst->dev from sk_setup_caps()
and sk_dst_gso_max_size().
Also use dst_dev_rcu() in ip6_dst_mtu_maybe_forward(),
and ip_dst_mtu_maybe_forward().
ip4_dst_hoplimit() can use dst_dev_net_rcu(). |
| In the Linux kernel, the following vulnerability has been resolved:
ALSA: pcm: Disable bottom softirqs as part of spin_lock_irq() on PREEMPT_RT
snd_pcm_group_lock_irq() acquires a spinlock_t and disables interrupts
via spin_lock_irq(). This also implicitly disables the handling of
softirqs such as TIMER_SOFTIRQ.
On PREEMPT_RT softirqs are preemptible and spin_lock_irq() does not
disable them. That means a timer can be invoked during spin_lock_irq()
on the same CPU. Due to synchronisations reasons local_bh_disable() has
a per-CPU lock named softirq_ctrl.lock which synchronizes individual
softirq against each other.
syz-bot managed to trigger a lockdep report where softirq_ctrl.lock is
acquired in hrtimer_cancel() in addition to hrtimer_run_softirq(). This
is a possible deadlock.
The softirq_ctrl.lock can not be made part of spin_lock_irq() as this
would lead to too much synchronisation against individual threads on the
system. To avoid the possible deadlock, softirqs must be manually
disabled before the lock is acquired.
Disable softirqs before the lock is acquired on PREEMPT_RT. |
| In the Linux kernel, the following vulnerability has been resolved:
jbd2: fix potential buffer head reference count leak
As in 'jbd2_fc_wait_bufs' if buffer isn't uptodate, will return -EIO without
update 'journal->j_fc_off'. But 'jbd2_fc_release_bufs' will release buffer head
from ‘j_fc_off - 1’ if 'bh' is NULL will terminal release which will lead to
buffer head buffer head reference count leak.
To solve above issue, update 'journal->j_fc_off' before return -EIO. |
| In the Linux kernel, the following vulnerability has been resolved:
xfs: fix out of bounds memory read error in symlink repair
xfs/286 produced this report on my test fleet:
==================================================================
BUG: KFENCE: out-of-bounds read in memcpy_orig+0x54/0x110
Out-of-bounds read at 0xffff88843fe9e038 (184B right of kfence-#184):
memcpy_orig+0x54/0x110
xrep_symlink_salvage_inline+0xb3/0xf0 [xfs]
xrep_symlink_salvage+0x100/0x110 [xfs]
xrep_symlink+0x2e/0x80 [xfs]
xrep_attempt+0x61/0x1f0 [xfs]
xfs_scrub_metadata+0x34f/0x5c0 [xfs]
xfs_ioc_scrubv_metadata+0x387/0x560 [xfs]
xfs_file_ioctl+0xe23/0x10e0 [xfs]
__x64_sys_ioctl+0x76/0xc0
do_syscall_64+0x4e/0x1e0
entry_SYSCALL_64_after_hwframe+0x4b/0x53
kfence-#184: 0xffff88843fe9df80-0xffff88843fe9dfea, size=107, cache=kmalloc-128
allocated by task 3470 on cpu 1 at 263329.131592s (192823.508886s ago):
xfs_init_local_fork+0x79/0xe0 [xfs]
xfs_iformat_local+0xa4/0x170 [xfs]
xfs_iformat_data_fork+0x148/0x180 [xfs]
xfs_inode_from_disk+0x2cd/0x480 [xfs]
xfs_iget+0x450/0xd60 [xfs]
xfs_bulkstat_one_int+0x6b/0x510 [xfs]
xfs_bulkstat_iwalk+0x1e/0x30 [xfs]
xfs_iwalk_ag_recs+0xdf/0x150 [xfs]
xfs_iwalk_run_callbacks+0xb9/0x190 [xfs]
xfs_iwalk_ag+0x1dc/0x2f0 [xfs]
xfs_iwalk_args.constprop.0+0x6a/0x120 [xfs]
xfs_iwalk+0xa4/0xd0 [xfs]
xfs_bulkstat+0xfa/0x170 [xfs]
xfs_ioc_fsbulkstat.isra.0+0x13a/0x230 [xfs]
xfs_file_ioctl+0xbf2/0x10e0 [xfs]
__x64_sys_ioctl+0x76/0xc0
do_syscall_64+0x4e/0x1e0
entry_SYSCALL_64_after_hwframe+0x4b/0x53
CPU: 1 UID: 0 PID: 1300113 Comm: xfs_scrub Not tainted 6.18.0-rc4-djwx #rc4 PREEMPT(lazy) 3d744dd94e92690f00a04398d2bd8631dcef1954
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-4.module+el8.8.0+21164+ed375313 04/01/2014
==================================================================
On further analysis, I realized that the second parameter to min() is
not correct. xfs_ifork::if_bytes is the size of the xfs_ifork::if_data
buffer. if_bytes can be smaller than the data fork size because:
(a) the forkoff code tries to keep the data area as large as possible
(b) for symbolic links, if_bytes is the ondisk file size + 1
(c) forkoff is always a multiple of 8.
Case in point: for a single-byte symlink target, forkoff will be
8 but the buffer will only be 2 bytes long.
In other words, the logic here is wrong and we walk off the end of the
incore buffer. Fix that. |
| In the Linux kernel, the following vulnerability has been resolved:
jfs: fix uninitialized waitqueue in transaction manager
The transaction manager initialization in txInit() was not properly
initializing TxBlock[0].waitor waitqueue, causing a crash when
txEnd(0) is called on read-only filesystems.
When a filesystem is mounted read-only, txBegin() returns tid=0 to
indicate no transaction. However, txEnd(0) still gets called and
tries to access TxBlock[0].waitor via tid_to_tblock(0), but this
waitqueue was never initialized because the initialization loop
started at index 1 instead of 0.
This causes a 'non-static key' lockdep warning and system crash:
INFO: trying to register non-static key in txEnd
Fix by ensuring all transaction blocks including TxBlock[0] have
their waitqueues properly initialized during txInit(). |
| In the Linux kernel, the following vulnerability has been resolved:
netpoll: Fix deadlock in memory allocation under spinlock
Fix a AA deadlock in refill_skbs() where memory allocation while holding
skb_pool->lock can trigger a recursive lock acquisition attempt.
The deadlock scenario occurs when the system is under severe memory
pressure:
1. refill_skbs() acquires skb_pool->lock (spinlock)
2. alloc_skb() is called while holding the lock
3. Memory allocator fails and calls slab_out_of_memory()
4. This triggers printk() for the OOM warning
5. The console output path calls netpoll_send_udp()
6. netpoll_send_udp() attempts to acquire the same skb_pool->lock
7. Deadlock: the lock is already held by the same CPU
Call stack:
refill_skbs()
spin_lock_irqsave(&skb_pool->lock) <- lock acquired
__alloc_skb()
kmem_cache_alloc_node_noprof()
slab_out_of_memory()
printk()
console_flush_all()
netpoll_send_udp()
skb_dequeue()
spin_lock_irqsave(&skb_pool->lock) <- deadlock attempt
This bug was exposed by commit 248f6571fd4c51 ("netpoll: Optimize skb
refilling on critical path") which removed refill_skbs() from the
critical path (where nested printk was being deferred), letting nested
printk being called from inside refill_skbs()
Refactor refill_skbs() to never allocate memory while holding
the spinlock.
Another possible solution to fix this problem is protecting the
refill_skbs() from nested printks, basically calling
printk_deferred_{enter,exit}() in refill_skbs(), then, any nested
pr_warn() would be deferred.
I prefer this approach, given I _think_ it might be a good idea to move
the alloc_skb() from GFP_ATOMIC to GFP_KERNEL in the future, so, having
the alloc_skb() outside of the lock will be necessary step.
There is a possible TOCTOU issue when checking for the pool length, and
queueing the new allocated skb, but, this is not an issue, given that
an extra SKB in the pool is harmless and it will be eventually used. |
