CVE-2024-40996 bpf: Avoid splat in pskb_pull_reason
A debug warning in the Linux kernel BPF subsystem can cause a kernel splat, potentially leading to a denial of service when specific debug configurations are enabled.
- 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-2024-40996?
CVE-2024-40996 is a high-severity denial of service vulnerability in Linux kernel, published on 12 Jul 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: 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.
Which versions are affected by CVE-2024-40996?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-40996?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2024-40996 being exploited?
There is no known exploitation of CVE-2024-40996 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2024-40996, DEBIAN-CVE-2024-40996, GHSA-5x23-w3hg-qfcx, UBUNTU-CVE-2024-40996.