Bug 2536728 (CVE-2026-90177)

Summary: CVE-2026-90177 kernel: bpf: Check pointer type for all atomic RMW paths
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: 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   
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A flaw was found in the Linux kernel's BPF (Berkeley Packet Filter) verifier. This vulnerability arises because the atomic Read-Modify-Write (RMW) verification process does not consistently check pointer types across all execution paths. Specifically, it only records the instruction pointer type when the destination is a specific memory region (PTR_TO_ARENA), allowing other paths to use ordinary pointers without proper type comparison. This inconsistency could enable a bypass of security checks within the BPF verifier, potentially leading to unintended operations or integrity issues within the kernel.
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Description OSIDB Bzimport 2026-09-17 19:21:39 UTC 
In the Linux kernel, the following vulnerability has been resolved:

bpf: Check pointer type for all atomic RMW paths

Atomic RMW verification records an instruction pointer type only when the
current destination is PTR_TO_ARENA. A second path can therefore reach the
same instruction with an ordinary pointer without comparing it against the
saved arena type.

The post-verification fixup uses the saved type to rewrite the instruction
to BPF_PROBE_ATOMIC for every path. Record the actual destination type for
all atomic RMW paths so the existing mismatch check rejects incompatible
uses of one instruction.
Comment 1 Keith Grant 2026-09-23 20:35:20 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-90177.mbox