The HMAC implementation (crypto/hmac.c) in the Linux kernel before 4.14.8 does not validate that the underlying cryptographic hash algorithm is unkeyed, allowing a local attacker able to use the AF_ALG-based hash interface (CONFIG_CRYPTO_USER_API_HASH) and the SHA-3 hash algorithm (CONFIG_CRYPTO_SHA3) to cause a kernel stack buffer overflow by executing a crafted sequence of system calls that encounter a missing SHA-3 initialization. References: http://marc.info/?t=151192100500002&r=1&w=2 An upstream patch: http://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=af3ff8045bbf3e32f1a448542e73abb4c8ceb6f1
Created kernel tracking bugs for this issue: Affects: fedora-all [bug 1528337]
This was fixed for Fedora with the 4.14.8 stable updates.
Statement: This issue does not affect the Linux kernel packages as shipped with Red Hat Enterprise Linux 5, 6, and 7, its real-time kernel and Red Hat Enterprise MRG 2. This issue affects the versions of the Linux kernel as shipped with Red Hat Enterprise Linux 7 for ARM 64 and Red Hat Enterprise Linux 7 for Power 9 LE. Future Linux kernel updates for the respective releases may address this issue.
This issue has been addressed in the following products: Red Hat Enterprise Linux 7 Via RHSA-2018:2948 http://access.redhat.com/errata/RHSA-2018:2948