CVE-2023-52676

Summary

In the Linux kernel, the following vulnerability has been resolved:

bpf: Guard stack limits against 32bit overflow

This patch promotes the arithmetic around checking stack bounds to be done in the 64-bit domain, instead of the current 32bit. The arithmetic implies adding together a 64-bit register with a int offset. The register was checked to be below 1<<29 when it was variable, but not when it was fixed. The offset either comes from an instruction (in which case it is 16 bit), from another register (in which case the caller checked it to be below 1<<29 [1]), or from the size of an argument to a kfunc (in which case it can be a u32 [2]). Between the register being inconsistently checked to be below 1<<29, and the offset being up to an u32, it appears that we were open to overflowing the ints which were currently used for arithmetic.

[1] https://github.com/torvalds/linux/blob/815fb87b753055df2d9e50f6cd80eb10235fe3e9/kernel/bpf/verifier.c#L7494-L7498 [2] https://github.com/torvalds/linux/blob/815fb87b753055df2d9e50f6cd80eb10235fe3e9/kernel/bpf/verifier.c#L11904

Affected Software

Weaknesses

ADP Enrichment

CISA ADP Vulnrichment

• SSVC:
• Exploitation: none
  • Automatable: no
  • Technical Impact: partial

CVE Program Container

Additional References

• https://git.kernel.org/stable/c/ad140fc856f0b1d5e2215bcb6d0cc247a86805a2
• https://git.kernel.org/stable/c/e5ad9ecb84405637df82732ee02ad741a5f782a6
• https://git.kernel.org/stable/c/1d38a9ee81570c4bd61f557832dead4d6f816760

References

• https://git.kernel.org/stable/c/ad140fc856f0b1d5e2215bcb6d0cc247a86805a2
• https://git.kernel.org/stable/c/e5ad9ecb84405637df82732ee02ad741a5f782a6
• https://git.kernel.org/stable/c/1d38a9ee81570c4bd61f557832dead4d6f816760

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