Linux: >> Linux Kernel >> 4.9.117 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
netfilter: arp_tables: fix IEEE1394 ARP payload parsing
Weiming Shi says:
"arp_packet_match() unconditionally parses the ARP payload assuming two
hardware addresses are present (source and target). However,
IPv4-over-IEEE1394 ARP (RFC 2734) omits the target hardware address
field, and arp_hdr_len() already accounts for this by returning a
shorter length for ARPHRD_IEEE1394 devices.
As a result, on IEEE1394 interfaces arp_packet_match() advances past a
nonexistent target hardware address and reads the wrong bytes for both
the target device address comparison and the target IP address. This
causes arptables rules to match against garbage data, leading to
incorrect filtering decisions: packets that should be accepted may be
dropped and vice versa.
The ARP stack in net/ipv4/arp.c (arp_create and arp_process) already
handles this correctly by skipping the target hardware address for
ARPHRD_IEEE1394. Apply the same pattern to arp_packet_match()."
Mangle the original patch to always return 0 (no match) in case user
matches on the target hardware address which is never present in
IEEE1394.
Note that this returns 0 (no match) for either normal and inverse match
because matching in the target hardware address in ARPHRD_IEEE1394 has
never been supported by arptables. This is intentional, matching on the
target hardware address should never evaluate true for ARPHRD_IEEE1394.
Moreover, adjust arpt_mangle to drop the packet too as AI suggests:
In arpt_mangle, the logic assumes a standard ARP layout. Because
IEEE1394 (FireWire) omits the target hardware address, the linear
pointer arithmetic miscalculates the offset for the target IP address.
This causes mangling operations to write to the wrong location, leading
to packet corruption. To ensure safety, this patch drops packets
(NF_DROP) when mangling is requested for these fields on IEEE1394
devices, as the current implementation cannot correctly map the FireWire
ARP payload.
This omits both mangling target hardware and IP address. Even if IP
address mangling should be possible in IEEE1394, this would require
to adjust arpt_mangle offset calculation, which has never been
supported.
Based on patch from Weiming Shi <bestswngs@gmail.com>.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-27
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: L2CAP: Fix null-ptr-deref in l2cap_sock_get_sndtimeo_cb()
Add the same NULL guard already present in
l2cap_sock_resume_cb() and l2cap_sock_ready_cb().
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-26
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: L2CAP: Fix null-ptr-deref in l2cap_sock_state_change_cb()
Add the same NULL guard already present in
l2cap_sock_resume_cb() and l2cap_sock_ready_cb().
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-26
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: L2CAP: Fix null-ptr-deref in l2cap_sock_new_connection_cb()
Add the same NULL guard already present in
l2cap_sock_resume_cb() and l2cap_sock_ready_cb().
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-26
In the Linux kernel, the following vulnerability has been resolved:
net: skbuff: propagate shared-frag marker through frag-transfer helpers
Two frag-transfer helpers (__pskb_copy_fclone() and skb_shift()) fail
to propagate the SKBFL_SHARED_FRAG bit in skb_shinfo()->flags when
moving frags from source to destination. __pskb_copy_fclone() defers
the rest of the shinfo metadata to skb_copy_header() after copying
frag descriptors, but that helper only carries over gso_{size,segs,
type} and never touches skb_shinfo()->flags; skb_shift() moves frag
descriptors directly and leaves flags untouched. As a result, the
destination skb keeps a reference to the same externally-owned or
page-cache-backed pages while reporting skb_has_shared_frag() as
false.
The mismatch is harmful in any in-place writer that uses
skb_has_shared_frag() to decide whether shared pages must be detoured
through skb_cow_data(). ESP input is one such writer (esp4.c,
esp6.c), and a single nft 'dup to <local>' rule -- or any other
nf_dup_ipv4() / xt_TEE caller -- is enough to land a pskb_copy()'d
skb in esp_input() with the marker stripped, letting an unprivileged
user write into the page cache of a root-owned read-only file via
authencesn-ESN stray writes.
Set SKBFL_SHARED_FRAG on the destination whenever frag descriptors
were actually moved from the source. skb_copy() and skb_copy_expand()
share skb_copy_header() too but linearize all paged data into freshly
allocated head storage and emerge with nr_frags == 0, so
skb_has_shared_frag() returns false on its own; they need no change.
The same omission exists in skb_gro_receive() and skb_gro_receive_list().
The former moves the incoming skb's frag descriptors into the
accumulator's last sub-skb via two paths (a direct frag-move loop and
the head_frag + memcpy path); the latter chains the incoming skb whole
onto p's frag_list. Downstream skb_segment() reads only
skb_shinfo(p)->flags, and skb_segment_list() reuses each sub-skb's
shinfo as the nskb -- both p and lp must carry the marker.
The same omission also exists in tcp_clone_payload(), which builds an
MTU probe skb by moving frag descriptors from skbs on sk_write_queue
into a freshly allocated nskb. The helper falls into the same family
and warrants the same fix for consistency; no TCP TX-side in-place
writer is currently known to reach a user page through this gap, but
a future consumer depending on the marker would regress silently.
The same omission exists in skb_segment(): the per-iteration flag
merge takes only head_skb's flag, and the inner switch that rebinds
frag_skb to list_skb on head_skb-frags exhaustion does not fold the
new frag_skb's flag into nskb. Fold frag_skb's flag at both sites
so segments drawing frags from frag_list members carry the marker.
CVSS Score
8.8
EPSS Score
0.001
Published
2026-05-23
In the Linux kernel, the following vulnerability has been resolved:
net: skbuff: preserve shared-frag marker during coalescing
skb_try_coalesce() can attach paged frags from @from to @to. If @from
has SKBFL_SHARED_FRAG set, the resulting @to skb can contain the same
externally-owned or page-cache-backed frags, but the shared-frag marker
is currently lost.
That breaks the invariant relied on by later in-place writers. In
particular, ESP input checks skb_has_shared_frag() before deciding
whether an uncloned nonlinear skb can skip skb_cow_data(). If TCP
receive coalescing has moved shared frags into an unmarked skb, ESP can
see skb_has_shared_frag() as false and decrypt in place over page-cache
backed frags.
Propagate SKBFL_SHARED_FRAG when skb_try_coalesce() transfers paged
frags. The tailroom copy path does not need the marker because it copies
bytes into @to's linear data rather than transferring frag descriptors.
CVSS Score
7.8
EPSS Score
0.037
Published
2026-05-23
In the Linux kernel, the following vulnerability has been resolved:
rtmutex: Use waiter::task instead of current in remove_waiter()
remove_waiter() is used by the slowlock paths, but it is also used for
proxy-lock rollback in rt_mutex_start_proxy_lock() when invoked from
futex_requeue().
In the latter case waiter::task is not current, but remove_waiter()
operates on current for the dequeue operation. That results in several
problems:
1) the rbtree dequeue happens without waiter::task::pi_lock being held
2) the waiter task's pi_blocked_on state is not cleared, which leaves a
dangling pointer primed for UAF around.
3) rt_mutex_adjust_prio_chain() operates on the wrong top priority waiter
task
Use waiter::task instead of current in all related operations in
remove_waiter() to cure those problems.
[ tglx: Fixup rt_mutex_adjust_prio_chain(), add a comment and amend the
changelog ]
CVSS Score
7.8
EPSS Score
0.001
Published
2026-05-21
In the Linux kernel, the following vulnerability has been resolved:
net/sched: sch_red: Replace direct dequeue call with peek and qdisc_dequeue_peeked
When red qdisc has children (eg qfq qdisc) whose peek() callback is
qdisc_peek_dequeued(), we could get a kernel panic. When the parent of such
qdiscs (eg illustrated in patch #3 as tbf) wants to retrieve an skb from
its child (red in this case), it will do the following:
1a. do a peek() - and when sensing there's an skb the child can offer, then
- the child in this case(red) calls its child's (qfq) peek.
qfq does the right thing and will return the gso_skb queue packet.
Note: if there wasnt a gso_skb entry then qfq will store it there.
1b. invoke a dequeue() on the child (red). And herein lies the problem.
- red will call the child's dequeue() which will essentially just
try to grab something of qfq's queue.
[ 78.667668][ T363] KASAN: null-ptr-deref in range [0x0000000000000048-0x000000000000004f]
[ 78.667927][ T363] CPU: 1 UID: 0 PID: 363 Comm: ping Not tainted 7.1.0-rc1-00033-g46f74a3f7d57-dirty #790 PREEMPT(full)
[ 78.668263][ T363] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[ 78.668486][ T363] RIP: 0010:qfq_dequeue+0x446/0xc90 [sch_qfq]
[ 78.668718][ T363] Code: 54 c0 e8 dd 90 00 f1 48 c7 c7 e0 03 54 c0 48 89 de e8 ce 90 00 f1 48 8d 7b 48 b8 ff ff 37 00 48 89 fa 48 c1 e0 2a 48 c1 ea 03 <80> 3c 02 00 74 05 e8 ef a1 e1 f1 48 8b 7b 48 48 8d 54 24 58 48 8d
[ 78.669312][ T363] RSP: 0018:ffff88810de573e0 EFLAGS: 00010216
[ 78.669533][ T363] RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
[ 78.669790][ T363] RDX: 0000000000000009 RSI: 0000000000000004 RDI: 0000000000000048
[ 78.670044][ T363] RBP: ffff888110dc4000 R08: ffffffffb1b0885a R09: fffffbfff6ba9078
[ 78.670297][ T363] R10: 0000000000000003 R11: ffff888110e31c80 R12: 0000001880000000
[ 78.670560][ T363] R13: ffff888110dc4150 R14: ffff888110dc42b8 R15: 0000000000000200
[ 78.670814][ T363] FS: 00007f66a8f09c40(0000) GS:ffff888163428000(0000) knlGS:0000000000000000
[ 78.671110][ T363] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 78.671324][ T363] CR2: 000055db4c6a30a8 CR3: 000000010da67000 CR4: 0000000000750ef0
[ 78.671585][ T363] PKRU: 55555554
[ 78.671713][ T363] Call Trace:
[ 78.671843][ T363] <TASK>
[ 78.671936][ T363] ? __pfx_qfq_dequeue+0x10/0x10 [sch_qfq]
[ 78.672148][ T363] ? __pfx__printk+0x10/0x10
[ 78.672322][ T363] ? srso_alias_return_thunk+0x5/0xfbef5
[ 78.672496][ T363] ? lockdep_hardirqs_on_prepare+0xa8/0x1a0
[ 78.672706][ T363] ? srso_alias_return_thunk+0x5/0xfbef5
[ 78.672875][ T363] ? trace_hardirqs_on+0x19/0x1a0
[ 78.673047][ T363] red_dequeue+0x65/0x270 [sch_red]
[ 78.673217][ T363] ? srso_alias_return_thunk+0x5/0xfbef5
[ 78.673385][ T363] tbf_dequeue.cold+0xb0/0x70c [sch_tbf]
[ 78.673566][ T363] __qdisc_run+0x169/0x1900
The right thing to do in #1b is to grab the skb off gso_skb queue.
This patchset fixes that issue by changing #1b to use qdisc_dequeue_peeked()
method instead.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-21
In the Linux kernel, the following vulnerability has been resolved:
crypto: pcrypt - Fix handling of MAY_BACKLOG requests
MAY_BACKLOG requests can return EBUSY. Handle them by checking
for that value and filtering out EINPROGRESS notifications.
CVSS Score
9.8
EPSS Score
0.006
Published
2026-05-19
In the Linux kernel, the following vulnerability has been resolved:
lib/crypto: mpi: Fix integer underflow in mpi_read_raw_from_sgl()
Yiming reports an integer underflow in mpi_read_raw_from_sgl() when
subtracting "lzeros" from the unsigned "nbytes".
For this to happen, the scatterlist "sgl" needs to occupy more bytes
than the "nbytes" parameter and the first "nbytes + 1" bytes of the
scatterlist must be zero. Under these conditions, the while loop
iterating over the scatterlist will count more zeroes than "nbytes",
subtract the number of zeroes from "nbytes" and cause the underflow.
When commit 2d4d1eea540b ("lib/mpi: Add mpi sgl helpers") originally
introduced the bug, it couldn't be triggered because all callers of
mpi_read_raw_from_sgl() passed a scatterlist whose length was equal to
"nbytes".
However since commit 63ba4d67594a ("KEYS: asymmetric: Use new crypto
interface without scatterlists"), the underflow can now actually be
triggered. When invoking a KEYCTL_PKEY_ENCRYPT system call with a
larger "out_len" than "in_len" and filling the "in" buffer with zeroes,
crypto_akcipher_sync_prep() will create an all-zero scatterlist used for
both the "src" and "dst" member of struct akcipher_request and thereby
fulfil the conditions to trigger the bug:
sys_keyctl()
keyctl_pkey_e_d_s()
asymmetric_key_eds_op()
software_key_eds_op()
crypto_akcipher_sync_encrypt()
crypto_akcipher_sync_prep()
crypto_akcipher_encrypt()
rsa_enc()
mpi_read_raw_from_sgl()
To the user this will be visible as a DoS as the kernel spins forever,
causing soft lockup splats as a side effect.
Fix it.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-19