CVE-2026-64313

Description

In the Linux kernel, the following vulnerability has been resolved: crypto: ecc - Fix carry overflow in vli multiplication The carry flag calculation fails when r01.m_high is saturated (0xFFFFFFFFFFFFFFFF) and addition of lower bits overflows. The condition (r01.m_high < product.m_high) doesn't handle the case where r01.m_high == product.m_high and an additional carry exists from lower-bit overflow. When commit 3c4b23901a0c ("crypto: ecdh - Add ECDH software support") introduced crypto/ecc.c, it split the muladd() function in the micro-ecc library into separate mul_64_64() and add_128_128() helpers. It seems the check got lost in translation. Add proper handling for this boundary by accounting for the carry from the lower addition.

References

• https://git.kernel.org/stable/c/24a54dfa06d09813b4802a374fad3d2c0e16a884
• https://git.kernel.org/stable/c/27b536a2ec8e2f85a0380c2d13c9ecbc7aaab406
• https://git.kernel.org/stable/c/5275e0fca256d081e2e7d4ba3dd8216c6e50d44e
• https://git.kernel.org/stable/c/677450e5ef850c4d28b7956aa01104548c2a894e
• https://git.kernel.org/stable/c/774ddddf5eb26eeca177350413e3e2bc50930ee9