Bug 2536187 (CVE-2026-92485)

Summary:	CVE-2026-92485 kernel: bpf: Fix WARNING in bpf_tracing_link_release
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in the Linux kernel's Berkeley Packet Filter (BPF) component. Incorrect handling of trampoline flags during the release of a BPF tracing link can lead to corruption of the trampoline. This corruption prevents the proper restoration of program instructions, which may result in a kernel warning and a denial of service (DoS) condition. A local attacker could potentially trigger this flaw.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-09-17 16:42:25 UTC

In the Linux kernel, the following vulnerability has been resolved:

bpf: Fix WARNING in bpf_tracing_link_release

The trampoline could be corrupted by the blindly
'tr->flags = BPF_TRAMP_F_TAIL_CALL_CTX' in verifier.

1. A fexit attached to a tail_call_reachable prog. 'tr->flags' became
   'BPF_TRAMP_F_CALL_ORIG | BPF_TRAMP_F_TAIL_CALL_CTX'. And, the
   trampoline would poke the target prog's nop insn using jmp insn instead
   of call insn.
2. Another fexit loaded with the same tail_call_reachable prog target.
   'tr->flags' became 'BPF_TRAMP_F_TAIL_CALL_CTX'.
3. Close the first fexit link. Due to no BPF_TRAMP_F_CALL_ORIG in
   'tr->flags', the trampoline will fail to restore the prog's nop insn
   using call insn.

[    3.410719] WARNING: kernel/bpf/syscall.c:3551 at bpf_tracing_link_release+0x53/0x60, CPU#1: test_progs/98
...
[    3.428793]  bpf_link_free+0x58/0x130
[    3.429293]  bpf_link_release+0x23/0x30

Fix the warning by updating 'tr->flags' with '|=' and lock.

Comment 1 gkamathe 2026-09-20 13:16:33 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-92485.mbox