A timing side channel vulnerability was discovered in the Linux Extended Verification Module (EVM). An attacker could use this to affect system integrity.
The problem exists because the vm_verify_hmac() function includes a use of memcmp(). This function is not safe to be used for comparing memory, allows timing side channel attacks; specifically a MAC forgery complexity drop from 2^128 to 2^12. This patch changes the memcmp() to the cryptographically safe crypto_memneq().
Original bug report:
This does not impact Fedora as CONFIG_EVM is not enabled.
This issue does not affect the Linux kernels as shipped with Red Hat Enterprise Linux 4,5 and 6.
This issue affects the Linux kernels as shipped with Red Hat Enterprise Linux 7 and kernel-rt packages and does not plan to be addressed in a future update.