CVE-2024-45020: bpf: Fix a kernel verifier crash in stacksafe()

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-09-11 · updated 2026-08-04
Weakness: CWE-787

Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix a kernel verifier crash in stacksafe() Daniel Hodges reported a kernel verifier crash when playing with sched-ext. Further investigation shows that the crash is due to invalid memory access in stacksafe(). More specifically, it is the following code: if (exact != NOT_EXACT && old->stack[spi].slot_type[i % BPF_REG_SIZE] != cur->stack[spi].slot_type[i % BPF_REG_SIZE]) return false; The 'i' iterates old->allocated_stack. If cur->allocated_stack < old->allocated_stack the out-of-bound access will happen. To fix the issue add 'i >= cur->allocated_stack' check such that if the condition is true, stacksafe() should fail. Otherwise, cur->stack[spi].slot_type[i % BPF_REG_SIZE] memory access is legal.

Affected products

Linux kernel: from 6.6.15 before 6.6.48; from 6.7 before 6.10.7; 6.11-rc1, 6.11-rc2, 6.11-rc3 — fixed in 6.10.7, 6.6.48

How to fix

Upgrade to a fixed version: Linux kernel 6.10.7, 6.6.48. Check the vendor advisory for mitigations.

References

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