Description
In the Linux kernel, the following vulnerability has been resolved: LoongArch: BPF: Don't override subprog's return value The verifier test `calls: div by 0 in subprog` triggers a panic at the ld.bu instruction. The ld.bu insn is trying to load byte from memory address returned by the subprog. The subprog actually set the correct address at the a5 register (dedicated register for BPF return values). But at commit 73c359d1d356 ("LoongArch: BPF: Sign-extend return values") we also sign extended a5 to the a0 register (return value in LoongArch). For function call insn, we later propagate the a0 register back to a5 register. This is right for native calls but wrong for bpf2bpf calls which expect zero-extended return value in a5 register. So only move a0 to a5 for native calls (i.e. non-BPF_PSEUDO_CALL).
Affected products
linux: linux kernel
References6
- git.kernel.org/stable/c/223d565d8892481684091cfbaf3466f2b0e289d3 Patch
- git.kernel.org/stable/c/60f3caff1492e5b8616b9578c4bedb5c0a88ed14 Patch
- git.kernel.org/stable/c/780628a780b622759d9e5adc76d15432144da1a3 Patch
- git.kernel.org/stable/c/7df2696256a034405d3c5a71b3a4c54725de4404 Patch
- git.kernel.org/stable/c/996e90ab446641553e8e21707b38b9709605e0e0 Patch
- git.kernel.org/stable/c/d99845f672cce0b610f7c51248ef95d7df63927e
Metrics
- CVSS 3.1
-
5.5
MEDIUM
Score source: NVD
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H - EPSS — exploit probability
- 0% percentile: 12 · as of 7 November 2026
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