CVE-2025-39802

Summary

In the Linux kernel, the following vulnerability has been resolved:

lib/crypto: arm/poly1305: Fix register corruption in no-SIMD contexts

Restore the SIMD usability check that was removed by commit 773426f4771b ("crypto: arm/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 may_use_simd() instead of the original crypto_simd_usable(), since poly1305_kunit won't rely on crypto_simd_disabled_for_test.

Affected Software

VendorProductVersion RangeStatus
LinuxLinux773426f4771bdd82ac5c834bf4c1775315c73a46 < 87bdfba903be7084cb3ee04032b14a81181fe413affected
LinuxLinux773426f4771bdd82ac5c834bf4c1775315c73a46 < 52c3e242f4d0043186b70d65460ba1767f27494aaffected
LinuxLinux6.16affected
LinuxLinux0 < 6.16unaffected
LinuxLinux6.16.4 <= 6.16.*unaffected
LinuxLinux6.17 <= *unaffected

Weaknesses

References