CVE-2024-44991 Affecting kernel-syms-azure package, versions <6.4.0-150600.8.14.1
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.
Do your applications use this vulnerable package?
In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.
Test your applications- Snyk IDSNYK-SLES156-KERNELSYMSAZURE-8169882
- published9 Oct 2024
- disclosed8 Oct 2024
Introduced: 8 Oct 2024
CVE-2024-44991 (opens in a new tab)How to fix?
Upgrade SLES:15.6 kernel-syms-azure to version 6.4.0-150600.8.14.1 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream kernel-syms-azure package and not the kernel-syms-azure package as distributed by SLES.
See How to fix? for SLES:15.6 relevant fixed versions and status.
In the Linux kernel, the following vulnerability has been resolved:
tcp: prevent concurrent execution of tcp_sk_exit_batch
Its possible that two threads call tcp_sk_exit_batch() concurrently, once from the cleanup_net workqueue, once from a task that failed to clone a new netns. In the latter case, error unwinding calls the exit handlers in reverse order for the 'failed' netns.
tcp_sk_exit_batch() calls tcp_twsk_purge(). Problem is that since commit b099ce2602d8 ("net: Batch inet_twsk_purge"), this function picks up twsk in any dying netns, not just the one passed in via exit_batch list.
This means that the error unwind of setup_net() can "steal" and destroy timewait sockets belonging to the exiting netns.
This allows the netns exit worker to proceed to call
WARN_ON_ONCE(!refcount_dec_and_test(&net->ipv4.tcp_death_row.tw_refcount));
without the expected 1 -> 0 transition, which then splats.
At same time, error unwind path that is also running inet_twsk_purge() will splat as well:
WARNING: .. at lib/refcount.c:31 refcount_warn_saturate+0x1ed/0x210 ... refcount_dec include/linux/refcount.h:351 [inline] inet_twsk_kill+0x758/0x9c0 net/ipv4/inet_timewait_sock.c:70 inet_twsk_deschedule_put net/ipv4/inet_timewait_sock.c:221 inet_twsk_purge+0x725/0x890 net/ipv4/inet_timewait_sock.c:304 tcp_sk_exit_batch+0x1c/0x170 net/ipv4/tcp_ipv4.c:3522 ops_exit_list+0x128/0x180 net/core/net_namespace.c:178 setup_net+0x714/0xb40 net/core/net_namespace.c:375 copy_net_ns+0x2f0/0x670 net/core/net_namespace.c:508 create_new_namespaces+0x3ea/0xb10 kernel/nsproxy.c:110
... because refcount_dec() of tw_refcount unexpectedly dropped to 0.
This doesn't seem like an actual bug (no tw sockets got lost and I don't see a use-after-free) but as erroneous trigger of debug check.
Add a mutex to force strict ordering: the task that calls tcp_twsk_purge() blocks other task from doing final _dec_and_test before mutex-owner has removed all tw sockets of dying netns.
References
- https://www.suse.com/security/cve/CVE-2024-44991.html
- https://bugzilla.suse.com/1230195
- https://git.kernel.org/stable/c/565d121b69980637f040eb4d84289869cdaabedf
- https://git.kernel.org/stable/c/99580ae890ec8bd98b21a2a9c6668f8f1555b62e
- https://git.kernel.org/stable/c/e3d9de3742f4d5c47ae35f888d3023a5b54fcd2f
- https://git.kernel.org/stable/c/f6fd2dbf584a4047ba88d1369ff91c9851261ec1