CVE-2021-3490

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Summary:

The eBPF ALU32 bounds tracking for bitwise ops (AND, OR and XOR) in the Linux kernel did not properly update 32-bit bounds, which could be turned into out of bounds reads and writes in the Linux kernel and therefore, arbitrary code execution. This issue was fixed via commit 049c4e13714e (“bpf: Fix alu32 const subreg bound tracking on bitwise operations”) (v5.13-rc4) and backported to the stable kernels in v5.12.4, v5.11.21, and v5.10.37. The AND/OR issues were introduced by commit 3f50f132d840 (“bpf: Verifier, do explicit ALU32 bounds tracking”) (5.7-rc1) and the XOR variant was introduced by 2921c90d4718 (“bpf:Fix a verifier failure with xor”) ( 5.10-rc1).

Reference Links(if available):

  • https://ubuntu.com/security/notices/USN-4949-1
  • https://www.zerodayinitiative.com/advisories/ZDI-21-606/
  • https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/commit/?id=049c4e13714ecbca567b4d5f6d563f05d431c80e
  • https://ubuntu.com/security/notices/USN-4950-1
  • https://www.openwall.com/lists/oss-security/2021/05/11/11
  • 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:U/C:H/I:H/A:H

    Links to Exploits(if available)

  • Available for Amazon Prime