Bug 2541306 (CVE-2026-98048)

Summary:	CVE-2026-98048 kernel: bpf: don't rewrite bpf_fastcall patterns entered by a jump
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 BPF (Berkeley Packet Filter) verifier. This vulnerability may allow a local user to achieve privilege escalation or cause a Denial of Service (DoS) through memory corruption. During helper call optimizations, the verifier improperly rewrites instruction sequences that are entered by a jump instruction. A local attacker with permission to load BPF programs can exploit this issue by submitting a specially crafted program, triggering unsound instruction transformations that bypass safety checks.	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 2026-09-25 11:17:31 UTC

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

bpf: don't rewrite bpf_fastcall patterns entered by a jump

mark_fastcall_pattern_for_call() must ensure that matched
"spill; call; fill" instruction series is not interrupted by a jump.
Otherwise the rewrite applied by bpf_remove_fastcall_spills_fills()
is not sound.

Record the instructions targeted by jumps in
insn_aux_data[*].jump_target when the CFG is built and use this flag
to stop growing a pattern at such an instruction. Jumps to the first
spill are fine.

Note that existing insn_aux_data[*].jmp_point field can't be reused,
as it marks subprogram return instructions.

Comment 1 Keith Grant 2026-09-28 23:23:47 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98048.mbox