Bug 2536499 (CVE-2026-90358)

Summary: CVE-2026-90358 kernel: bpf, x86: Fix trampoline stack size for 128-bit arguments
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) x86 trampoline. When processing 128-bit arguments, the system incorrectly calculates the required stack size for saving registers. This under-allocation leads to memory corruption by overwriting adjacent stack slots. A local attacker could potentially exploit this vulnerability to cause a denial of service or escalate privileges.
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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 2026-09-17 18:13:52 UTC 
In the Linux kernel, the following vulnerability has been resolved:

bpf, x86: Fix trampoline stack size for 128-bit arguments

btf_distill_func_proto() accepts a function argument up to 16 bytes, so a
128-bit scalar such as __int128 reaches the x86 trampoline with
arg_size == 16. But the current implementation assumes an __int128
argument only needs one register, so the register save area is
under-allocated and save_args() overwrites adjacent stack slots.

Compute the register count from arg_size for all arguments to fix it.
Comment 1 gkamathe 2026-09-22 07:07:05 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-90358.mbox