Linux: >> Linux Kernel >> 3.8.4 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
dst: fix races in rt6_uncached_list_del() and rt_del_uncached_list()
syzbot was able to crash the kernel in rt6_uncached_list_flush_dev()
in an interesting way [1]
Crash happens in list_del_init()/INIT_LIST_HEAD() while writing
list->prev, while the prior write on list->next went well.
static inline void INIT_LIST_HEAD(struct list_head *list)
{
WRITE_ONCE(list->next, list); // This went well
WRITE_ONCE(list->prev, list); // Crash, @list has been freed.
}
Issue here is that rt6_uncached_list_del() did not attempt to lock
ul->lock, as list_empty(&rt->dst.rt_uncached) returned
true because the WRITE_ONCE(list->next, list) happened on the other CPU.
We might use list_del_init_careful() and list_empty_careful(),
or make sure rt6_uncached_list_del() always grabs the spinlock
whenever rt->dst.rt_uncached_list has been set.
A similar fix is neeed for IPv4.
[1]
BUG: KASAN: slab-use-after-free in INIT_LIST_HEAD include/linux/list.h:46 [inline]
BUG: KASAN: slab-use-after-free in list_del_init include/linux/list.h:296 [inline]
BUG: KASAN: slab-use-after-free in rt6_uncached_list_flush_dev net/ipv6/route.c:191 [inline]
BUG: KASAN: slab-use-after-free in rt6_disable_ip+0x633/0x730 net/ipv6/route.c:5020
Write of size 8 at addr ffff8880294cfa78 by task kworker/u8:14/3450
CPU: 0 UID: 0 PID: 3450 Comm: kworker/u8:14 Tainted: G L syzkaller #0 PREEMPT_{RT,(full)}
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: netns cleanup_net
Call Trace:
<TASK>
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
print_report+0xca/0x240 mm/kasan/report.c:482
kasan_report+0x118/0x150 mm/kasan/report.c:595
INIT_LIST_HEAD include/linux/list.h:46 [inline]
list_del_init include/linux/list.h:296 [inline]
rt6_uncached_list_flush_dev net/ipv6/route.c:191 [inline]
rt6_disable_ip+0x633/0x730 net/ipv6/route.c:5020
addrconf_ifdown+0x143/0x18a0 net/ipv6/addrconf.c:3853
addrconf_notify+0x1bc/0x1050 net/ipv6/addrconf.c:-1
notifier_call_chain+0x19d/0x3a0 kernel/notifier.c:85
call_netdevice_notifiers_extack net/core/dev.c:2268 [inline]
call_netdevice_notifiers net/core/dev.c:2282 [inline]
netif_close_many+0x29c/0x410 net/core/dev.c:1785
unregister_netdevice_many_notify+0xb50/0x2330 net/core/dev.c:12353
ops_exit_rtnl_list net/core/net_namespace.c:187 [inline]
ops_undo_list+0x3dc/0x990 net/core/net_namespace.c:248
cleanup_net+0x4de/0x7b0 net/core/net_namespace.c:696
process_one_work kernel/workqueue.c:3257 [inline]
process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340
worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
</TASK>
Allocated by task 803:
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
unpoison_slab_object mm/kasan/common.c:340 [inline]
__kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366
kasan_slab_alloc include/linux/kasan.h:253 [inline]
slab_post_alloc_hook mm/slub.c:4953 [inline]
slab_alloc_node mm/slub.c:5263 [inline]
kmem_cache_alloc_noprof+0x18d/0x6c0 mm/slub.c:5270
dst_alloc+0x105/0x170 net/core/dst.c:89
ip6_dst_alloc net/ipv6/route.c:342 [inline]
icmp6_dst_alloc+0x75/0x460 net/ipv6/route.c:3333
mld_sendpack+0x683/0xe60 net/ipv6/mcast.c:1844
mld_send_cr net/ipv6/mcast.c:2154 [inline]
mld_ifc_work+0x83e/0xd60 net/ipv6/mcast.c:2693
process_one_work kernel/workqueue.c:3257 [inline]
process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340
worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entr
---truncated---
CVSS Score
4.7
EPSS Score
0.0
Published
2026-01-25
In the Linux kernel, the following vulnerability has been resolved:
net/sched: sch_qfq: do not free existing class in qfq_change_class()
Fixes qfq_change_class() error case.
cl->qdisc and cl should only be freed if a new class and qdisc
were allocated, or we risk various UAF.
CVSS Score
5.5
EPSS Score
0.0
Published
2026-01-25
In the Linux kernel, the following vulnerability has been resolved:
libceph: replace overzealous BUG_ON in osdmap_apply_incremental()
If the osdmap is (maliciously) corrupted such that the incremental
osdmap epoch is different from what is expected, there is no need to
BUG. Instead, just declare the incremental osdmap to be invalid.
CVSS Score
5.5
EPSS Score
0.0
Published
2026-01-23
In the Linux kernel, the following vulnerability has been resolved:
wifi: avoid kernel-infoleak from struct iw_point
struct iw_point has a 32bit hole on 64bit arches.
struct iw_point {
void __user *pointer; /* Pointer to the data (in user space) */
__u16 length; /* number of fields or size in bytes */
__u16 flags; /* Optional params */
};
Make sure to zero the structure to avoid disclosing 32bits of kernel data
to user space.
CVSS Score
3.3
EPSS Score
0.0
Published
2026-01-23
In the Linux kernel, the following vulnerability has been resolved:
net/sched: sch_qfq: Fix NULL deref when deactivating inactive aggregate in qfq_reset
`qfq_class->leaf_qdisc->q.qlen > 0` does not imply that the class
itself is active.
Two qfq_class objects may point to the same leaf_qdisc. This happens
when:
1. one QFQ qdisc is attached to the dev as the root qdisc, and
2. another QFQ qdisc is temporarily referenced (e.g., via qdisc_get()
/ qdisc_put()) and is pending to be destroyed, as in function
tc_new_tfilter.
When packets are enqueued through the root QFQ qdisc, the shared
leaf_qdisc->q.qlen increases. At the same time, the second QFQ
qdisc triggers qdisc_put and qdisc_destroy: the qdisc enters
qfq_reset() with its own q->q.qlen == 0, but its class's leaf
qdisc->q.qlen > 0. Therefore, the qfq_reset would wrongly deactivate
an inactive aggregate and trigger a null-deref in qfq_deactivate_agg:
[ 0.903172] BUG: kernel NULL pointer dereference, address: 0000000000000000
[ 0.903571] #PF: supervisor write access in kernel mode
[ 0.903860] #PF: error_code(0x0002) - not-present page
[ 0.904177] PGD 10299b067 P4D 10299b067 PUD 10299c067 PMD 0
[ 0.904502] Oops: Oops: 0002 [#1] SMP NOPTI
[ 0.904737] CPU: 0 UID: 0 PID: 135 Comm: exploit Not tainted 6.19.0-rc3+ #2 NONE
[ 0.905157] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014
[ 0.905754] RIP: 0010:qfq_deactivate_agg (include/linux/list.h:992 (discriminator 2) include/linux/list.h:1006 (discriminator 2) net/sched/sch_qfq.c:1367 (discriminator 2) net/sched/sch_qfq.c:1393 (discriminator 2))
[ 0.906046] Code: 0f 84 4d 01 00 00 48 89 70 18 8b 4b 10 48 c7 c2 ff ff ff ff 48 8b 78 08 48 d3 e2 48 21 f2 48 2b 13 48 8b 30 48 d3 ea 8b 4b 18 0
Code starting with the faulting instruction
===========================================
0: 0f 84 4d 01 00 00 je 0x153
6: 48 89 70 18 mov %rsi,0x18(%rax)
a: 8b 4b 10 mov 0x10(%rbx),%ecx
d: 48 c7 c2 ff ff ff ff mov $0xffffffffffffffff,%rdx
14: 48 8b 78 08 mov 0x8(%rax),%rdi
18: 48 d3 e2 shl %cl,%rdx
1b: 48 21 f2 and %rsi,%rdx
1e: 48 2b 13 sub (%rbx),%rdx
21: 48 8b 30 mov (%rax),%rsi
24: 48 d3 ea shr %cl,%rdx
27: 8b 4b 18 mov 0x18(%rbx),%ecx
...
[ 0.907095] RSP: 0018:ffffc900004a39a0 EFLAGS: 00010246
[ 0.907368] RAX: ffff8881043a0880 RBX: ffff888102953340 RCX: 0000000000000000
[ 0.907723] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
[ 0.908100] RBP: ffff888102952180 R08: 0000000000000000 R09: 0000000000000000
[ 0.908451] R10: ffff8881043a0000 R11: 0000000000000000 R12: ffff888102952000
[ 0.908804] R13: ffff888102952180 R14: ffff8881043a0ad8 R15: ffff8881043a0880
[ 0.909179] FS: 000000002a1a0380(0000) GS:ffff888196d8d000(0000) knlGS:0000000000000000
[ 0.909572] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 0.909857] CR2: 0000000000000000 CR3: 0000000102993002 CR4: 0000000000772ef0
[ 0.910247] PKRU: 55555554
[ 0.910391] Call Trace:
[ 0.910527] <TASK>
[ 0.910638] qfq_reset_qdisc (net/sched/sch_qfq.c:357 net/sched/sch_qfq.c:1485)
[ 0.910826] qdisc_reset (include/linux/skbuff.h:2195 include/linux/skbuff.h:2501 include/linux/skbuff.h:3424 include/linux/skbuff.h:3430 net/sched/sch_generic.c:1036)
[ 0.911040] __qdisc_destroy (net/sched/sch_generic.c:1076)
[ 0.911236] tc_new_tfilter (net/sched/cls_api.c:2447)
[ 0.911447] rtnetlink_rcv_msg (net/core/rtnetlink.c:6958)
[ 0.911663] ? __pfx_rtnetlink_rcv_msg (net/core/rtnetlink.c:6861)
[ 0.911894] netlink_rcv_skb (net/netlink/af_netlink.c:2550)
[ 0.912100] netlink_unicast (net/netlink/af_netlink.c:1319 net/netlink/af_netlink.c:1344)
[ 0.912296] ? __alloc_skb (net/core/skbuff.c:706)
[ 0.912484] netlink_sendmsg (net/netlink/af
---truncated---
CVSS Score
5.5
EPSS Score
0.0
Published
2026-01-21
In the Linux kernel, the following vulnerability has been resolved:
crypto: seqiv - Do not use req->iv after crypto_aead_encrypt
As soon as crypto_aead_encrypt is called, the underlying request
may be freed by an asynchronous completion. Thus dereferencing
req->iv after it returns is invalid.
Instead of checking req->iv against info, create a new variable
unaligned_info and use it for that purpose instead.
CVSS Score
5.5
EPSS Score
0.0
Published
2026-01-14
In the Linux kernel, the following vulnerability has been resolved:
via_wdt: fix critical boot hang due to unnamed resource allocation
The VIA watchdog driver uses allocate_resource() to reserve a MMIO
region for the watchdog control register. However, the allocated
resource was not given a name, which causes the kernel resource tree
to contain an entry marked as "<BAD>" under /proc/iomem on x86
platforms.
During boot, this unnamed resource can lead to a critical hang because
subsequent resource lookups and conflict checks fail to handle the
invalid entry properly.
CVSS Score
5.5
EPSS Score
0.0
Published
2026-01-14
In the Linux kernel, the following vulnerability has been resolved:
ACPICA: Avoid walking the Namespace if start_node is NULL
Although commit 0c9992315e73 ("ACPICA: Avoid walking the ACPI Namespace
if it is not there") fixed the situation when both start_node and
acpi_gbl_root_node are NULL, the Linux kernel mainline now still crashed
on Honor Magicbook 14 Pro [1].
That happens due to the access to the member of parent_node in
acpi_ns_get_next_node(). The NULL pointer dereference will always
happen, no matter whether or not the start_node is equal to
ACPI_ROOT_OBJECT, so move the check of start_node being NULL
out of the if block.
Unfortunately, all the attempts to contact Honor have failed, they
refused to provide any technical support for Linux.
The bad DSDT table's dump could be found on GitHub [2].
DMI: HONOR FMB-P/FMB-P-PCB, BIOS 1.13 05/08/2025
[ rjw: Subject adjustment, changelog edits ]
CVSS Score
5.5
EPSS Score
0.0
Published
2026-01-14
In the Linux kernel, the following vulnerability has been resolved:
hwmon: (w83791d) Convert macros to functions to avoid TOCTOU
The macro FAN_FROM_REG evaluates its arguments multiple times. When used
in lockless contexts involving shared driver data, this leads to
Time-of-Check to Time-of-Use (TOCTOU) race conditions, potentially
causing divide-by-zero errors.
Convert the macro to a static function. This guarantees that arguments
are evaluated only once (pass-by-value), preventing the race
conditions.
Additionally, in store_fan_div, move the calculation of the minimum
limit inside the update lock. This ensures that the read-modify-write
sequence operates on consistent data.
Adhere to the principle of minimal changes by only converting macros
that evaluate arguments multiple times and are used in lockless
contexts.
CVSS Score
4.7
EPSS Score
0.0
Published
2026-01-14
In the Linux kernel, the following vulnerability has been resolved:
crypto: af_alg - zero initialize memory allocated via sock_kmalloc
Several crypto user API contexts and requests allocated with
sock_kmalloc() were left uninitialized, relying on callers to
set fields explicitly. This resulted in the use of uninitialized
data in certain error paths or when new fields are added in the
future.
The ACVP patches also contain two user-space interface files:
algif_kpp.c and algif_akcipher.c. These too rely on proper
initialization of their context structures.
A particular issue has been observed with the newly added
'inflight' variable introduced in af_alg_ctx by commit:
67b164a871af ("crypto: af_alg - Disallow multiple in-flight AIO requests")
Because the context is not memset to zero after allocation,
the inflight variable has contained garbage values. As a result,
af_alg_alloc_areq() has incorrectly returned -EBUSY randomly when
the garbage value was interpreted as true:
https://github.com/gregkh/linux/blame/master/crypto/af_alg.c#L1209
The check directly tests ctx->inflight without explicitly
comparing against true/false. Since inflight is only ever set to
true or false later, an uninitialized value has triggered
-EBUSY failures. Zero-initializing memory allocated with
sock_kmalloc() ensures inflight and other fields start in a known
state, removing random issues caused by uninitialized data.
CVSS Score
5.5
EPSS Score
0.0
Published
2026-01-14