Detections
Analytics
CVE-2021-3491
high
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).
References
https://www.zerodayinitiative.com/advisories/ZDI-21-589/
https://www.openwall.com/lists/oss-security/2021/05/11/13
https://ubuntu.com/security/notices/USN-4950-1
https://ubuntu.com/security/notices/USN-4949-1