CVE-2026-90195 in Linux
要約
〜によって MITRE • 2026年09月17日
In the Linux kernel, the following vulnerability has been resolved:
riscv, bpf: Fix missing sign-ext for signed 1-byte and 2-byte kfunc args
On RV64, the ABI requires sign-extension for signed 1-byte and 2-byte kfunc args. However, the RV64 JIT currently does not perform sign-extension for such kfunc args.
Before commit 7ce090afbf72 ("bpf: Infer zext_dst based on static register liveness analysis"), state pruning could potentially omit zero-extension of 32-bit subregisters, which inadvertently masked the above issue by making the args appear as if they had been properly sign-extended. After that commit, the problem is exposed, causing the kfunc_call/kfunc_call_test4 selftest to fail.
Fix this by extending the existing sign-extension logic to handle signed 1-byte and 2-byte kfunc args as well.
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