bpf: Fix undefined behavior in interpreter sdiv/smod for INT_MIN
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Fix
- Fixed in 6.6.131, 6.12.80, 6.18.21, 6.19.11
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: no
- Technical impact: total
Summary
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 the interpreter's sdiv32/smod32 handlers. s32 is the only affected case -- the s64 division/modulo handlers do not use abs().
Timeline
- CVE published
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: total
- Record last updated
Affected versions
- Linux Linux
From ec0e2da95f72d4a46050a4d994e4fe471474fd80 · fixed in 694ea55f1b1c74f9942d91ec366ae9e822422e42; From ec0e2da95f72d4a46050a4d994e4fe471474fd80 · fixed in 9ab1227765c446942f290c83382f0b19887c55cf; From ec0e2da95f72d4a46050a4d994e4fe471474fd80 · fixed in f14ca604c0ff274fba19f73f1f0485c0047c1396; From ec0e2da95f72d4a46050a4d994e4fe471474fd80 · fixed in 0d5d8c3ce45c734aaf3c51cbef59155a6746157d; From ec0e2da95f72d4a46050a4d994e4fe471474fd80 · fixed in c77b30bd1dcb61f66c640ff7d2757816210c7cb0
- Linux Linux
6.6
- KernelLinux
From 6.6.0 · fixed in 6.6.131; From 6.7.0 · fixed in 6.12.80; From 6.13.0 · fixed in 6.18.21; From 6.19.0 · fixed in 6.19.11