Bug 2554970 (CVE-2026-98599)

Summary: CVE-2026-98599 kernel: bpf: Reject non-negative offsets in stack_slot_obj_get_spi()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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 Berkeley Packet Filter (BPF) verifier. A local attacker can exploit this flaw to cause kernel memory corruption and potentially achieve privilege escalation or a denial of service (system crash). This vulnerability occurs because the verifier fails to reject non-negative stack offsets, allowing a crafted BPF program to improperly access and interpret memory outside the allocated stack boundaries.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Description OSIDB Bzimport 2026-10-18 15:36:32 UTC 
In the Linux kernel, the following vulnerability has been resolved:

bpf: Reject non-negative offsets in stack_slot_obj_get_spi()

bpf_get_spi() computes (-off - 1) / BPF_REG_SIZE using C division,
which truncates toward zero. For off == 0, this produces spi 0, the
same index used by the valid stack slot at fp-8.

stack_slot_obj_get_spi() currently checks alignment and the resulting
spi bounds, but does not reject the non-negative offset itself. It can
therefore validate a PTR_TO_STACK register holding fp+0 against an
iterator stored at fp-8 even though the runtime receives the actual fp+0
pointer. An effectful iterator kfunc can then interpret memory outside
the BPF stack as iterator state.

Reject non-negative offsets before converting the offset to an spi. All
valid stack objects begin at a negative offset from the frame pointer.