Linux: >> Linux Kernel >> 2.6.14 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
xfs: close crash window in attr dabtree inactivation
When inactivating an inode with node-format extended attributes,
xfs_attr3_node_inactive() invalidates all child leaf/node blocks via
xfs_trans_binval(), but intentionally does not remove the corresponding
entries from their parent node blocks. The implicit assumption is that
xfs_attr_inactive() will truncate the entire attr fork to zero extents
afterwards, so log recovery will never reach the root node and follow
those stale pointers.
However, if a log shutdown occurs after the leaf/node block cancellations
commit but before the attr bmap truncation commits, this assumption
breaks. Recovery replays the attr bmap intact (the inode still has
attr fork extents), but suppresses replay of all cancelled leaf/node
blocks, maybe leaving them as stale data on disk. On the next mount,
xlog_recover_process_iunlinks() retries inactivation and attempts to
read the root node via the attr bmap. If the root node was not replayed,
reading the unreplayed root block triggers a metadata verification
failure immediately; if it was replayed, following its child pointers
to unreplayed child blocks triggers the same failure:
XFS (pmem0): Metadata corruption detected at
xfs_da3_node_read_verify+0x53/0x220, xfs_da3_node block 0x78
XFS (pmem0): Unmount and run xfs_repair
XFS (pmem0): First 128 bytes of corrupted metadata buffer:
00000000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00000030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00000040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00000050: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00000060: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00000070: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
XFS (pmem0): metadata I/O error in "xfs_da_read_buf+0x104/0x190" at daddr 0x78 len 8 error 117
Fix this in two places:
In xfs_attr3_node_inactive(), after calling xfs_trans_binval() on a
child block, immediately remove the entry that references it from the
parent node in the same transaction. This eliminates the window where
the parent holds a pointer to a cancelled block. Once all children are
removed, the now-empty root node is converted to a leaf block within the
same transaction. This node-to-leaf conversion is necessary for crash
safety. If the system shutdown after the empty node is written to the
log but before the second-phase bmap truncation commits, log recovery
will attempt to verify the root block on disk. xfs_da3_node_verify()
does not permit a node block with count == 0; such a block will fail
verification and trigger a metadata corruption shutdown. on the other
hand, leaf blocks are allowed to have this transient state.
In xfs_attr_inactive(), split the attr fork truncation into two explicit
phases. First, truncate all extents beyond the root block (the child
extents whose parent references have already been removed above).
Second, invalidate the root block and truncate the attr bmap to zero in
a single transaction. The two operations in the second phase must be
atomic: as long as the attr bmap has any non-zero length, recovery can
follow it to the root block, so the root block invalidation must commit
together with the bmap-to-zero truncation.
CVSS Score
4.7
EPSS Score
0.001
Published
2026-05-01
In the Linux kernel, the following vulnerability has been resolved:
net/x25: Fix potential double free of skb
When alloc_skb fails in x25_queue_rx_frame it calls kfree_skb(skb) at
line 48 and returns 1 (error).
This error propagates back through the call chain:
x25_queue_rx_frame returns 1
|
v
x25_state3_machine receives the return value 1 and takes the else
branch at line 278, setting queued=0 and returning 0
|
v
x25_process_rx_frame returns queued=0
|
v
x25_backlog_rcv at line 452 sees queued=0 and calls kfree_skb(skb)
again
This would free the same skb twice. Looking at x25_backlog_rcv:
net/x25/x25_in.c:x25_backlog_rcv() {
...
queued = x25_process_rx_frame(sk, skb);
...
if (!queued)
kfree_skb(skb);
}
CVSS Score
9.8
EPSS Score
0.005
Published
2026-05-01
In the Linux kernel, the following vulnerability has been resolved:
netfilter: ip6t_eui64: reject invalid MAC header for all packets
`eui64_mt6()` derives a modified EUI-64 from the Ethernet source address
and compares it with the low 64 bits of the IPv6 source address.
The existing guard only rejects an invalid MAC header when
`par->fragoff != 0`. For packets with `par->fragoff == 0`, `eui64_mt6()`
can still reach `eth_hdr(skb)` even when the MAC header is not valid.
Fix this by removing the `par->fragoff != 0` condition so that packets
with an invalid MAC header are rejected before accessing `eth_hdr(skb)`.
CVSS Score
9.4
EPSS Score
0.003
Published
2026-04-25
In the Linux kernel, the following vulnerability has been resolved:
netfilter: ip6t_rt: reject oversized addrnr in rt_mt6_check()
Reject rt match rules whose addrnr exceeds IP6T_RT_HOPS.
rt_mt6() expects addrnr to stay within the bounds of rtinfo->addrs[].
Validate addrnr during rule installation so malformed rules are rejected
before the match logic can use an out-of-range value.
CVSS Score
7.1
EPSS Score
0.001
Published
2026-04-25
In the Linux kernel, the following vulnerability has been resolved:
xfrm: clear trailing padding in build_polexpire()
build_expire() clears the trailing padding bytes of struct
xfrm_user_expire after setting the hard field via memset_after(),
but the analogous function build_polexpire() does not do this for
struct xfrm_user_polexpire.
The padding bytes after the __u8 hard field are left
uninitialized from the heap allocation, and are then sent to
userspace via netlink multicast to XFRMNLGRP_EXPIRE listeners,
leaking kernel heap memory contents.
Add the missing memset_after() call, matching build_expire().
CVSS Score
5.5
EPSS Score
0.001
Published
2026-04-24
In the Linux kernel, the following vulnerability has been resolved:
fbdev: tdfxfb: avoid divide-by-zero on FBIOPUT_VSCREENINFO
Much like commit 19f953e74356 ("fbdev: fb_pm2fb: Avoid potential divide
by zero error"), we also need to prevent that same crash from happening
in the udlfb driver as it uses pixclock directly when dividing, which
will crash.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-04-24
In the Linux kernel, the following vulnerability has been resolved:
smb: server: avoid double-free in smb_direct_free_sendmsg after smb_direct_flush_send_list()
smb_direct_flush_send_list() already calls smb_direct_free_sendmsg(),
so we should not call it again after post_sendmsg()
moved it to the batch list.
CVSS Score
9.8
EPSS Score
0.005
Published
2026-04-24
In the Linux kernel, the following vulnerability has been resolved:
smb: client: avoid double-free in smbd_free_send_io() after smbd_send_batch_flush()
smbd_send_batch_flush() already calls smbd_free_send_io(),
so we should not call it again after smbd_post_send()
moved it to the batch list.
CVSS Score
9.8
EPSS Score
0.005
Published
2026-04-24
In the Linux kernel, the following vulnerability has been resolved:
media: em28xx: fix use-after-free in em28xx_v4l2_open()
em28xx_v4l2_open() reads dev->v4l2 without holding dev->lock,
creating a race with em28xx_v4l2_init()'s error path and
em28xx_v4l2_fini(), both of which free the em28xx_v4l2 struct
and set dev->v4l2 to NULL under dev->lock.
This race leads to two issues:
- use-after-free in v4l2_fh_init() when accessing vdev->ctrl_handler,
since the video_device is embedded in the freed em28xx_v4l2 struct.
- NULL pointer dereference in em28xx_resolution_set() when accessing
v4l2->norm, since dev->v4l2 has been set to NULL.
Fix this by moving the mutex_lock() before the dev->v4l2 read and
adding a NULL check for dev->v4l2 under the lock.
CVSS Score
7.8
EPSS Score
0.001
Published
2026-04-24
In the Linux kernel, the following vulnerability has been resolved:
media: mediatek: vcodec: fix use-after-free in encoder release path
The fops_vcodec_release() function frees the context structure (ctx)
without first cancelling any pending or running work in ctx->encode_work.
This creates a race window where the workqueue handler (mtk_venc_worker)
may still be accessing the context memory after it has been freed.
Race condition:
CPU 0 (release path) CPU 1 (workqueue)
--------------------- ------------------
fops_vcodec_release()
v4l2_m2m_ctx_release()
v4l2_m2m_cancel_job()
// waits for m2m job "done"
mtk_venc_worker()
v4l2_m2m_job_finish()
// m2m job "done"
// BUT worker still running!
// post-job_finish access:
other ctx dereferences
// UAF if ctx already freed
// returns (job "done")
kfree(ctx) // ctx freed
Root cause: The v4l2_m2m_ctx_release() only waits for the m2m job
lifecycle (via TRANS_RUNNING flag), not the workqueue lifecycle.
After v4l2_m2m_job_finish() is called, the m2m framework considers
the job complete and v4l2_m2m_ctx_release() returns, but the worker
function continues executing and may still access ctx.
The work is queued during encode operations via:
queue_work(ctx->dev->encode_workqueue, &ctx->encode_work)
The worker function accesses ctx->m2m_ctx, ctx->dev, and other ctx
fields even after calling v4l2_m2m_job_finish().
This vulnerability was confirmed with KASAN by running an instrumented
test module that widens the post-job_finish race window. KASAN detected:
BUG: KASAN: slab-use-after-free in mtk_venc_worker+0x159/0x180
Read of size 4 at addr ffff88800326e000 by task kworker/u8:0/12
Workqueue: mtk_vcodec_enc_wq mtk_venc_worker
Allocated by task 47:
__kasan_kmalloc+0x7f/0x90
fops_vcodec_open+0x85/0x1a0
Freed by task 47:
__kasan_slab_free+0x43/0x70
kfree+0xee/0x3a0
fops_vcodec_release+0xb7/0x190
Fix this by calling cancel_work_sync(&ctx->encode_work) before kfree(ctx).
This ensures the workqueue handler is both cancelled (if pending) and
synchronized (waits for any running handler to complete) before the
context is freed.
Placement rationale: The fix is placed after v4l2_ctrl_handler_free()
and before list_del_init(&ctx->list). At this point, all m2m operations
are done (v4l2_m2m_ctx_release() has returned), and we need to ensure
the workqueue is synchronized before removing ctx from the list and
freeing it.
Note: The open error path does NOT need cancel_work_sync() because
INIT_WORK() only initializes the work structure - it does not schedule
it. Work is only scheduled later during device_run() operations.
CVSS Score
7.8
EPSS Score
0.001
Published
2026-04-24