CVE-2024-50281

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

KEYS: trusted: dcp: fix NULL dereference in AEAD crypto operation

When sealing or unsealing a key blob we currently do not wait for the AEAD cipher operation to finish and simply return after submitting the request. If there is some load on the system we can exit before the cipher operation is done and the buffer we read from/write to is already removed from the stack. This will e.g. result in NULL pointer dereference errors in the DCP driver during blob creation.

Fix this by waiting for the AEAD cipher operation to finish before resuming the seal and unseal calls.

A low impact race condition was found in the Linux kernel trusted keys DCP (Data Co-Processor) backend (security/keys/trusted-keys/trusted_dcp.c). When sealing or unsealing a trusted key blob, the code submitted an AEAD cipher request and returned without waiting for the operation to complete. Under system load, the seal or unseal call could return while the cipher operation was still in progress and the stack buffers it reads from or writes to had already been removed, leading to a NULL pointer dereference in the DCP driver during key blob creation. A local user able to perform trusted-key seal or unseal operations through the DCP backend could use this flaw to cause a denial of service; confidentiality and integrity are not affected. The vulnerable code was introduced in upstream Linux kernel 6.11. All currently maintained Red Hat Enterprise Linux 6, 7, 8, and 9 kernel and kernel-rt streams are recorded as not affected by this flaw; the affected Red Hat product scope is limited to the Fedora community kernel, where a fix is being pursued through the community (delegated) process. The upstream CVE record scores this issue 7.8 (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H), while Red Hat assigns a lower severity (CVSS 3.1 score 5.5, AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H, Low impact) because the premature return and resulting NULL pointer dereference affect availability only.

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.