CVE-2026-31525
type: TechArticle
description: In the Linux kernel, the following vulnerability has been resolved: bpf: Fix undefined behavior in interpreter sdiv/smod for INT_MIN The BPF interpreter's signed 32-bit division and modulo handlers use the kernel abs() macro on s32 operands. The abs() macro documentation (include/linux/math.h) explicitly states the result is undefined when the input is the type minimum. When DST contains S32_MIN (0x80000000), abs((s32)DST) triggers undefined behavior and returns S32_MIN unchanged on arm64/x86. This value is then sign-extended to u64 as 0xFFFFFFFF80000000, causing do_div() to compute the wrong result. The verifier's abstract interpretation (scalar32_min_max_sdiv) computes the mathematically correct result for range tracking, creating a verifier/interpreter mismatch that can be exploited for out-of-bounds map value access. Introduce abs_s32() which handles S32_MIN correctly by casting to u32 before negating, avoiding signed overflow entirely. Replace all 8 abs((s32)...) call sites in
date published: 2026-04-22T14:16:52.607
license: https://creativecommons.org/publicdomain/zero/1.0/
source: https://nvd.nist.gov/vuln/detail/CVE-2026-31525
publisher: AI Analytics
source organization: NIST National Vulnerability Database
main entity: Thing
  additional type: Vulnerability
  score: 7.8
  severity: HIGH
keywords: CWE-787

AI Analytics
type: Organization