CVE-2026-31525
CVE-2026-31525
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().
Fixes and workarounds
Fix
The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67Fix
The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67Fix
The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67Fix
The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67Fix
The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67Affected products and versions
| Product | Versions | Authority |
|---|---|---|
| linux_kernel linux |
≥ 6.6; < 6.6.131 (affected, custom) | NVD |
| linux_kernel linux |
≥ 6.7; < 6.12.80 (affected, custom) | NVD |
| linux_kernel linux |
≥ 6.13; < 6.18.21 (affected, custom) | NVD |
| linux_kernel linux |
≥ 6.19; < 6.19.11 (affected, custom) | NVD |
| linux_kernel linux |
7.0 (affected, custom) | NVD |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
NVD applicability configurations (1)
These expressions retain AND/OR operators, negation, and required environmental products. A listed product is not sufficient to establish exposure when additional conditions apply.
[
{
"negate": false,
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.6.131",
"versionStartIncluding": "6.6",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.12.80",
"versionStartIncluding": "6.7",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.21",
"versionStartIncluding": "6.13",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.19.11",
"versionStartIncluding": "6.19",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
],
"operator": "OR"
}
]CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 3.1 / 7.8 high |
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H | NVD: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://git.kernel.org/stable/c/0d5d8c3ce45c734aaf3c51cbef59155a6746157d416baaa9-dc9f-4396-8d5f-8c081fb06d67 · Patch
- https://git.kernel.org/stable/c/694ea55f1b1c74f9942d91ec366ae9e822422e42416baaa9-dc9f-4396-8d5f-8c081fb06d67 · Patch
- https://git.kernel.org/stable/c/9ab1227765c446942f290c83382f0b19887c55cf416baaa9-dc9f-4396-8d5f-8c081fb06d67 · Patch
- https://git.kernel.org/stable/c/c77b30bd1dcb61f66c640ff7d2757816210c7cb0416baaa9-dc9f-4396-8d5f-8c081fb06d67 · Patch
- https://git.kernel.org/stable/c/f14ca604c0ff274fba19f73f1f0485c0047c1396416baaa9-dc9f-4396-8d5f-8c081fb06d67 · Patch
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