CVE-2023-53599

/// Technical description

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

crypto: af_alg - Fix missing initialisation affecting gcm-aes-s390

Fix af_alg_alloc_areq() to initialise areq->first_rsgl.sgl.sgt.sgl to point

to the scatterlist array in areq->first_rsgl.sgl.sgl.

Without this, the gcm-aes-s390 driver will oops when it tries to do

gcm_walk_start() on req->dst because req->dst is set to the value of

areq->first_rsgl.sgl.sgl by _aead_recvmsg() calling

aead_request_set_crypt().

The problem comes if an empty ciphertext is passed: the loop in

af_alg_get_rsgl() just passes straight out and doesn't set areq->first_rsgl

up.

This isn't a problem on x86_64 using gcmaes_crypt_by_sg() because, as far

as I can tell, that ignores req->dst and only uses req->src[*].

[*] Is this a bug in aesni-intel_glue.c?

The s390x oops looks something like:

Unable to handle kernel pointer dereference in virtual kernel address space

Failing address: 0000000a00000000 TEID: 0000000a00000803

Fault in home sp

/// 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