CVE-2024-40996: bpf: Avoid splat in pskb_pull_reason

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-07-12 · updated 2026-06-17

Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Avoid splat in pskb_pull_reason syzkaller builds (CONFIG_DEBUG_NET=y) frequently trigger a debug hint in pskb_may_pull. We'd like to retain this debug check because it might hint at integer overflows and other issues (kernel code should pull headers, not huge value). In bpf case, this splat isn't interesting at all: such (nonsensical) bpf programs are typically generated by a fuzzer anyway. Do what Eric suggested and suppress such warning. For CONFIG_DEBUG_NET=n we don't need the extra check because pskb_may_pull will do the right thing: return an error without the WARN() backtrace.

Affected products

Linux kernel: from 6.1.86 before 6.1.96; from 6.6.27 before 6.6.36; from 6.9 before 6.9.7; 6.10-rc1, 6.10-rc2, 6.10-rc3, 6.10-rc4 — fixed in 6.1.96, 6.6.36, 6.9.7

How to fix

Upgrade to a fixed version: Linux kernel 6.1.96, 6.6.36, 6.9.7. Check the vendor advisory for mitigations.

References

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