CVE-2024-49854

Summary

In the Linux kernel, the following vulnerability has been resolved: block, bfq: fix uaf for accessing waker_bfqq after splitting After commit 42c306ed7233 ("block, bfq: don't break merge chain in bfq_split_bfqq()"), if the current procress is the last holder of bfqq, the bfqq can be freed after bfq_split_bfqq(). Hence recored the bfqq and then access bfqq->waker_bfqq may trigger UAF. What's more, the waker_bfqq may in the merge chain of bfqq, hence just recored waker_bfqq is still not safe. Fix the problem by adding a helper bfq_waker_bfqq() to check if bfqq->waker_bfqq is in the merge chain, and current procress is the only holder.

Impact & exploitability

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products we track (1)

Recommendation

Apply the vendor fix promptly. Open any affected product above for its exact safe version.

Official patch: https://git.kernel.org/stable/c/0780451f03bf518bc032a7c584de8f92e2d39d7f ↗

Additional information

• NVD record
• https://git.kernel.org/stable/c/0780451f03bf518bc032a7c584de8f92e2d39d7fPatch
• https://git.kernel.org/stable/c/0b8bda0ff17156cd3f60944527c9d8c9f99f1583Patch
• https://git.kernel.org/stable/c/1ba0403ac6447f2d63914fb760c44a3b19c44eafPatch
• https://git.kernel.org/stable/c/63a07379fdb6c72450cb05294461c6016b8b7726Patch
• https://git.kernel.org/stable/c/cae58d19121a70329cf971359e2518c93fec04fePatch
• https://git.kernel.org/stable/c/de0456460f2abf921e356ed2bd8da87a376680bdPatch
• https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html