CVE-2021-3491

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Summary:

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//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).

Reference Links(if available):

  • https://ubuntu.com/security/notices/USN-4949-1
  • https://ubuntu.com/security/notices/USN-4950-1
  • https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d1f82808877bb10d3deee7cf3374a4eb3fb582db
  • https://www.zerodayinitiative.com/advisories/ZDI-21-589/
  • https://www.openwall.com/lists/oss-security/2021/05/11/13
  • CVSS Score (if available)

    v2: / MEDIUMAV:L/AC:L/Au:N/C:C/I:C/A:C

    v3: / HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

    Links to Exploits(if available)

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