CVE-2021-3491
Description
The io_uring subsystem in the Linux kernel allowed the MAX_RW_COUNT limit to be bypassed in the PROVIDE_BUFFERS operation, which led to negative values being usedin mem_rw when reading /proc/<PID>/mem. This could be used to create a heap overflow leading to arbitrary code execution in the kernel. It was addressed via commit d1f82808877b ("io_uring: truncate lengths larger than MAX_RW_COUNT on provide buffers") (v5.13-rc1) and backported to the stable kernels in v5.12.4, v5.11.21, and v5.10.37. It was introduced in ddf0322db79c ("io_uring: add IORING_OP_PROVIDE_BUFFERS") (v5.7-rc1).
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
Vendor advisory: debian — https://security-tracker.debian.org/tracker/CVE-2021-3491
Vendor advisory: suse — https://www.suse.com/security/cve/CVE-2021-3491.html
OS impact
| OS | Version | Status | Fixed in |
|---|---|---|---|
| arch | fixed | 5.10.37-1 | |
| sles | affected | | |
| debian | bookworm | fixed | 5.10.38-1 |
| debian | bullseye | fixed | 5.10.38-1 |
| debian | forky | fixed | 5.10.38-1 |
| debian | sid | fixed | 5.10.38-1 |
| debian | trixie | fixed | 5.10.38-1 |
References
Verify integrity in audit chain (admin only). AS-IS.