Bug 2536702 (CVE-2026-92517)

Summary:	CVE-2026-92517 kernel: bpf, riscv: Fix extable handling for arena load_acquire
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) subsystem, specifically in the handling of `extable` entries for `arena load_acquire` operations on RISC-V architecture. Due to improper exception handling, a stale register value on fault can be leaked through a map, potentially leading to information disclosure. Additionally, a missing `extable` entry can cause a kernel crash, resulting in a Denial of Service (DoS). A local attacker could exploit this vulnerability to gain access to sensitive kernel memory or cause system instability.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
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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 19:09:40 UTC

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

bpf, riscv: Fix extable handling for arena load_acquire

emit_atomic_ld_st() returns 1 to have build_body() skip the zext after
a sub-word load_acquire. The caller does "ret = ret ?:
add_exception_handler(...)", which skips add_exception_handler() on any
non-zero ret, so the extable entry is missing and a faulting
PROBE_ATOMIC load_acquire oopses.

REG_DONT_CLEAR_MARKER leaves rd stale on fault, and the verifier still
thinks the load overwrote it, so a program can leak it through a map.

Check ret >= 0 before calling add_exception_handler(), and pass rd for
LOAD_ACQ so the fault zeroes rd like a PROBE_MEM load. Return ret
unchanged for the zext skip.

Comment 1 gkamathe 2026-09-21 05:21:33 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-92517.mbox