CVE-2026-90195

Summary

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 Software

VendorProductVersion RangeStatus
LinuxLinux443574b033876c85a35de4c65c14f7fe092222b2 < 555fc6f1caf00ce7005e732b688da26c0dc3c5c5affected
LinuxLinux443574b033876c85a35de4c65c14f7fe092222b2 < 801ae90f8ce099187e6224cec7d72d07a4df0324affected
LinuxLinux443574b033876c85a35de4c65c14f7fe092222b2 < 71dbd143be598954ae103feadd12692aeb0f2f88affected
LinuxLinux443574b033876c85a35de4c65c14f7fe092222b2 < f2aaa621591093cfe8224a25ef2f04a3b1e304b0affected
LinuxLinux6.9affected
LinuxLinux0 < 6.9unaffected
LinuxLinux6.12.110 <= 6.12.*unaffected
LinuxLinux6.18.52 <= 6.18.*unaffected
LinuxLinux7.2.6 <= 7.2.*unaffected
LinuxLinux7.3-rc1 <= *unaffected

Weaknesses

References