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Linux vulnerability

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 `int`s 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

Published 17 May 2024Updated 14 Sep 20269 sources
CVSS 7.8
Overview Sources History

What happened

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 `int`s 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 versions

Linux: f3c4b01689d392373301e6e60d1b02c5b4020afc through before ad1754f86a87fe74912fb542b23ff24ada4e3307 (git); 01f810ace9ed37255f27608a0864abebccf0aab3 through before 4ba97610399e83d29d1086a0827d33172539b49b (git); 01f810ace9ed37255f27608a0864abebccf0aab3 through before e160b2ed94a20fa940369ebd914277f88005e70d (git); 01f810ace9ed37255f27608a0864abebccf0aab3 through before ad140fc856f0b1d5e2215bcb6d0cc247a86805a2 (git); 01f810ace9ed37255f27608a0864abebccf0aab3 through before e5ad9ecb84405637df82732ee02ad741a5f782a6 (git); 01f810ace9ed37255f27608a0864abebccf0aab3 through before 1d38a9ee81570c4bd61f557832dead4d6f816760 (git); d1b725ea5d104caea250427899f4e2e3ab15b4fc (git); 5.10.33 through before 5.10.270 (semver); 5.11.17 through before 5.12 (semver); 5.12 Fixed: See vendor advisory.

Why it matters

Review the vendor advisory and exposure of the affected product to determine operational impact.

Detection & mitigation

  • Apply vendor-provided updates or mitigations.
  • Review affected product exposure and access logs.

Public PoC references

No public PoC reference has passed the current publication threshold.

CorrectionsReport an issue