In the Linux kernel, the following vulnerability has been resolved:
lib/crypto: arm64/poly1305: Fix register corruption in no-SIMD contexts
Restore the SIMD usability check that was removed by commit a59e5468a921 ("crypto: arm64/poly1305 - Add block-only interface").
This safety check is cheap and is well worth eliminating a footgun. While the Poly1305 functions should not be called when SIMD registers are unusable, if they are anyway, they should just do the right thing instead of corrupting random tasks' registers and/or computing incorrect MACs. Fixing this is also needed for poly1305_kunit to pass.
Just use mayusesimd() instead of the original cryptosimdusable(), since poly1305kunit won't rely on cryptosimddisabledfor_test.
{
"cna_assigner": "Linux",
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/39xxx/CVE-2025-39804.json"
}