GHSA-WM8W-4PX2-2HP8
Vulnerability from github – Published: 2026-09-17 18:31 – Updated: 2026-09-17 18:31In 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": [],
"aliases": [
"CVE-2026-90195"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-17T17:17:14Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nriscv, bpf: Fix missing sign-ext for signed 1-byte and 2-byte kfunc args\n\nOn RV64, the ABI requires sign-extension for signed 1-byte and 2-byte kfunc\nargs. However, the RV64 JIT currently does not perform sign-extension for\nsuch kfunc args.\n\nBefore commit 7ce090afbf72 (\"bpf: Infer zext_dst based on static register\nliveness analysis\"), state pruning could potentially omit zero-extension\nof 32-bit subregisters, which inadvertently masked the above issue by making\nthe args appear as if they had been properly sign-extended. After that\ncommit, the problem is exposed, causing the kfunc_call/kfunc_call_test4\nselftest to fail.\n\nFix this by extending the existing sign-extension logic to handle signed\n1-byte and 2-byte kfunc args as well.",
"id": "GHSA-wm8w-4px2-2hp8",
"modified": "2026-09-17T18:31:55Z",
"published": "2026-09-17T18:31:55Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-90195"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/555fc6f1caf00ce7005e732b688da26c0dc3c5c5"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/71dbd143be598954ae103feadd12692aeb0f2f88"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/801ae90f8ce099187e6224cec7d72d07a4df0324"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f2aaa621591093cfe8224a25ef2f04a3b1e304b0"
}
],
"schema_version": "1.4.0",
"severity": []
}
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