CVE-2023-53373

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

crypto: seqiv - Handle EBUSY correctly

As it is seqiv only handles the special return value of EINPROGERSS, which means that in all other cases it will free data related to the request.

However, as the caller of seqiv may specify MAY_BACKLOG, we also need to expect EBUSY and treat it in the same way. Otherwise backlogged requests will trigger a use-after-free.

The flaw is in the seqiv IV generator and can lead to a use-after-free when backlogged crypto requests return -EBUSY. Triggering it is easier locally by flooding the kernel crypto API (e.g. via AF_ALG or many concurrent AEAD requests) because the attacker must create backlog conditions. Remote triggering is much harder and only realistic for specific configurations (for example an in-kernel IPsec/TLS path that uses seqiv for AEAD). In practice this means an unprivileged local user with access to the kernel crypto interface is the most likely threat vector, while a remote attacker would need the target to both use seqiv and be inducible into heavy crypto backlog.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.