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.
Analysis
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Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | |||||||||||||||||||||
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| Linux | Linux | unaffected |
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| Linux | Linux | affected |
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No vendor fix or workaround currently provided.
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Thu, 17 Sep 2026 16:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | 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. | |
| Title | riscv, bpf: Fix missing sign-ext for signed 1-byte and 2-byte kfunc args | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-09-17T16:07:14.979Z
Reserved: 2026-09-11T19:38:34.792Z
Link: CVE-2026-90195
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-09-17T17:17:14.280
Modified: 2026-09-17T17:17:14.280
Link: CVE-2026-90195
Redhat
No data.
OpenCVE Enrichment
No data.
No weakness.