CVE-2023-53536

/// Technical description

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

blk-crypto: make blk_crypto_evict_key() more robust

If blk_crypto_evict_key() sees that the key is still in-use (due to a

bug) or that ->keyslot_evict failed, it currently just returns while

leaving the key linked into the keyslot management structures.

However, blk_crypto_evict_key() is only called in contexts such as inode

eviction where failure is not an option. So actually the caller

proceeds with freeing the blk_crypto_key regardless of the return value

of blk_crypto_evict_key().

These two assumptions don't match, and the result is that there can be a

use-after-free in blk_crypto_reprogram_all_keys() after one of these

errors occurs. (Note, these errors *shouldn't* happen; we're just

talking about what happens if they do anyway.)

Fix this by making blk_crypto_evict_key() unlink the key from the

keyslot management structures even on failure.

Also improve some comments.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References