cbcvebase.
CVE-2024-43887
published 2024-08-26

CVE-2024-43887: In the Linux kernel, the following vulnerability has been resolved: net/tcp: Disable TCP-AO static key after RCU grace period The lifetime of TCP-AO static_key…

PriorityP418medium4.7CVSS 3.1
AVLACHPRLUINSUCNINAH
EPSS
0.19%
8.8th percentile
In the Linux kernel, the following vulnerability has been resolved: net/tcp: Disable TCP-AO static key after RCU grace period The lifetime of TCP-AO static_key is the same as the last tcp_ao_info. On the socket destruction tcp_ao_info ceases to be with RCU grace period, while tcp-ao static branch is currently deferred destructed. The static key definition is : DEFINE_STATIC_KEY_DEFERRED_FALSE(tcp_ao_needed, HZ); which means that if RCU grace period is delayed by more than a second and tcp_ao_needed is in the process of disablement, other CPUs may yet see tcp_ao_info which atent dead, but soon-to-be. And that breaks the assumption of static_key_fast_inc_not_disabled(). See the comment near the definition: > * The caller must make sure that the static key can't get disabled while > * in this function. It doesn't patch jump labels, only adds a user to > * an already enabled static key. Originally it was introduced in commit eb8c507296f6 ("jump_label: Prevent key->enabled int overflow"), which is needed for the atomic contexts, one of which would be the creation of a full socket from a request socket. In that atomic context, it's known by the presence of the key (md5/ao) that the static branch is already enabled. So, the ref counter for that static branch is just incremented instead of holding the proper mutex. static_key_fast_inc_not_disabled() is just a helper for such usage case. But it must not be used if the static branch could get disabled in parallel as it's not protected by jump_label_mutex and as a result, races with jump_label_update() implementation details. Happened on netdev test-bot[1], so not a theoretical issue: [] jump_label: Fatal kernel bug, unexpected op at tcp_inbound_hash+0x1a7/0x870 [ffffffffa8c4e9b7] (eb 50 0f 1f 44 != 66 90 0f 1f 00)) size:2 type:1 [] ------------[ cut here ]------------ [] kernel BUG at arch/x86/kernel/jump_label.c:73! [] Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN NOPTI [] CPU: 3 PID: 243 Comm: kworker/3:3 Not tai

Affected

9 ranges
VendorProductVersion rangeFixed in
debianlinux< linux 6.10.6-1 (forky)linux 6.10.6-1 (forky)
linuxlinux
linuxlinux>= 67fa83f7c86a86913ab9cd5a13b4bebd8d2ebb43 < 954d55a59b2501f4a9bd693b40ce45a1c46cb2b3954d55a59b2501f4a9bd693b40ce45a1c46cb2b3
linuxlinux>= 67fa83f7c86a86913ab9cd5a13b4bebd8d2ebb43 < 14ab4792ee120c022f276a7e4768f4dcb08f0cdd14ab4792ee120c022f276a7e4768f4dcb08f0cdd
linuxlinux_kernel
linuxlinux_kernel>= 0 < 6.10.6-16.10.6-1
linuxlinux_kernel>= 0 < 6.10.6-16.10.6-1
linuxlinux_kernel>= 0 < 6.8.0-50.516.8.0-50.51
linuxlinux_kernel>= 6.7 < 6.10.56.10.5

CVSS provenance

nvdv3.14.7MEDIUMCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
osv5.5MEDIUM
vendor_ubuntu5.5MEDIUM
vendor_debian4.7LOW
vendor_redhat4.7MEDIUM
Stop checking back — get the weekly exploitation signal.

Every Monday: what got weaponized or added to CISA KEV in the last seven days — each CVE cross-linked to its PoC, Nuclei template, and detection rule. Free, one email a week, unsubscribe in one click.