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CVE-2026-90195

riscv, bpf: Fix missing sign-ext for signed 1-byte and 2-byte kfunc args PUBLISHED

Description (CNA)

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.

Affected (CNA)

Vendor / productVersions
Linux / Linuxaffected 443574b033876c85a35de4c65c14f7fe092222b2 before 555fc6f1caf00ce7005e732b688da26c0dc3c5c5; affected 443574b033876c85a35de4c65c14f7fe092222b2 before 801ae90f8ce099187e6224cec7d72d07a4df0324; affected 443574b033876c85a35de4c65c14f7fe092222b2 before 71dbd143be598954ae103feadd12692aeb0f2f88; affected 443574b033876c85a35de4c65c14f7fe092222b2 before f2aaa621591093cfe8224a25ef2f04a3b1e304b0
Linux / Linuxaffected 6.9; unaffected 0 before 6.9; unaffected 6.12.110 through 6.12.*; unaffected 6.18.52 through 6.18.*; unaffected 7.2.6 through 7.2.*; unaffected 7.3 through *

CWE

No CWE identifiers supplied.

References