Use After Free Affecting kernel-default package, versions <5.14.21-150400.24.136.1
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-SLES154-KERNELDEFAULT-8169972
- published9 Oct 2024
- disclosed8 Oct 2024
Introduced: 8 Oct 2024
CVE-2024-44946 (opens in a new tab)How to fix?
Upgrade SLES:15.4 kernel-default to version 5.14.21-150400.24.136.1 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream kernel-default package and not the kernel-default package as distributed by SLES.
See How to fix? for SLES:15.4 relevant fixed versions and status.
In the Linux kernel, the following vulnerability has been resolved:
kcm: Serialise kcm_sendmsg() for the same socket.
syzkaller reported UAF in kcm_release(). [0]
The scenario is
Thread A builds a skb with MSG_MORE and sets kcm->seq_skb.
Thread A resumes building skb from kcm->seq_skb but is blocked by sk_stream_wait_memory()
Thread B calls sendmsg() concurrently, finishes building kcm->seq_skb and puts the skb to the write queue
Thread A faces an error and finally frees skb that is already in the write queue
kcm_release() does double-free the skb in the write queue
When a thread is building a MSG_MORE skb, another thread must not touch it.
Let's add a per-sk mutex and serialise kcm_sendmsg().
[0]: BUG: KASAN: slab-use-after-free in __skb_unlink include/linux/skbuff.h:2366 [inline] BUG: KASAN: slab-use-after-free in __skb_dequeue include/linux/skbuff.h:2385 [inline] BUG: KASAN: slab-use-after-free in __skb_queue_purge_reason include/linux/skbuff.h:3175 [inline] BUG: KASAN: slab-use-after-free in __skb_queue_purge include/linux/skbuff.h:3181 [inline] BUG: KASAN: slab-use-after-free in kcm_release+0x170/0x4c8 net/kcm/kcmsock.c:1691 Read of size 8 at addr ffff0000ced0fc80 by task syz-executor329/6167
CPU: 1 PID: 6167 Comm: syz-executor329 Tainted: G B 6.8.0-rc5-syzkaller-g9abbc24128bc #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024 Call trace: dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:291 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:298 __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xd0/0x124 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:377 [inline] print_report+0x178/0x518 mm/kasan/report.c:488 kasan_report+0xd8/0x138 mm/kasan/report.c:601 __asan_report_load8_noabort+0x20/0x2c mm/kasan/report_generic.c:381 __skb_unlink include/linux/skbuff.h:2366 [inline] __skb_dequeue include/linux/skbuff.h:2385 [inline] __skb_queue_purge_reason include/linux/skbuff.h:3175 [inline] __skb_queue_purge include/linux/skbuff.h:3181 [inline] kcm_release+0x170/0x4c8 net/kcm/kcmsock.c:1691 __sock_release net/socket.c:659 [inline] sock_close+0xa4/0x1e8 net/socket.c:1421 __fput+0x30c/0x738 fs/file_table.c:376 ____fput+0x20/0x30 fs/file_table.c:404 task_work_run+0x230/0x2e0 kernel/task_work.c:180 exit_task_work include/linux/task_work.h:38 [inline] do_exit+0x618/0x1f64 kernel/exit.c:871 do_group_exit+0x194/0x22c kernel/exit.c:1020 get_signal+0x1500/0x15ec kernel/signal.c:2893 do_signal+0x23c/0x3b44 arch/arm64/kernel/signal.c:1249 do_notify_resume+0x74/0x1f4 arch/arm64/kernel/entry-common.c:148 exit_to_user_mode_prepare arch/arm64/kernel/entry-common.c:169 [inline] exit_to_user_mode arch/arm64/kernel/entry-common.c:178 [inline] el0_svc+0xac/0x168 arch/arm64/kernel/entry-common.c:713 el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598
Allocated by task 6166: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x40/0x78 mm/kasan/common.c:68 kasan_save_alloc_info+0x70/0x84 mm/kasan/generic.c:626 unpoison_slab_object mm/kasan/common.c:314 [inline] __kasan_slab_alloc+0x74/0x8c mm/kasan/common.c:340 kasan_slab_alloc include/linux/kasan.h:201 [inline] slab_post_alloc_hook mm/slub.c:3813 [inline] slab_alloc_node mm/slub.c:3860 [inline] kmem_cache_alloc_node+0x204/0x4c0 mm/slub.c:3903 __alloc_skb+0x19c/0x3d8 net/core/skbuff.c:641 alloc_skb include/linux/skbuff.h:1296 [inline] kcm_sendmsg+0x1d3c/0x2124 net/kcm/kcmsock.c:783 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg net/socket.c:745 [inline] sock_sendmsg+0x220/0x2c0 net/socket.c:768 splice_to_socket+0x7cc/0xd58 fs/splice.c:889 do_splice_from fs/splice.c:941 [inline] direct_splice_actor+0xec/0x1d8 fs/splice.c:1164 splice_direct_to_actor+0x438/0xa0c fs/splice.c:1108 do_splice_direct_actor ---truncated---
References
- https://www.suse.com/security/cve/CVE-2024-44946.html
- https://bugzilla.suse.com/1230015
- https://bugzilla.suse.com/1230016
- https://git.kernel.org/stable/c/00425508f30baa5ab6449a1f478480ca7cffa6da
- https://git.kernel.org/stable/c/72da240aafb142630cf16adc803ccdacb3780849
- https://git.kernel.org/stable/c/807067bf014d4a3ae2cc55bd3de16f22a01eb580
- https://git.kernel.org/stable/c/9c8d544ed619f704e2b70e63e08ab75630c2ea23
- https://git.kernel.org/stable/c/6633b17840bf828921254d788ccd15602843fe9b
- https://git.kernel.org/stable/c/8c9cdbf600143bd6835c8b8351e5ac956da79aec
- https://git.kernel.org/stable/c/eb06c8d3022ce6738711191c89f9b3e9cfb91914
- https://git.kernel.org/stable/c/fa6c23fe6dcac8c8bd63920ee8681292a2bd544e