CVE-2024-45020 bpf: Fix a kernel verifier crash in stacksafe()
A local attacker can trigger a kernel crash via invalid memory access in the BPF verifier, causing a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2024-45020?
CVE-2024-45020 is a high-severity memory corruption vulnerability in Linux kernel, published on 11 Sep 2024. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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.
Weakness: CWE-787
Which versions are affected by CVE-2024-45020?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-45020?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2024-45020 being exploited?
There is no known exploitation of CVE-2024-45020 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-49221, BELL-CVE-2024-45020, DEBIAN-CVE-2024-45020, GHSA-jf76-2c3p-rhc5, UBUNTU-CVE-2024-45020.