CVE-2024-35895 bpf, sockmap: Prevent lock inversion deadlock in map delete elem
A local attacker can trigger a kernel deadlock via BPF tracing programs, 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-2024-35895?
CVE-2024-35895 is a medium-severity vulnerability in Debian Debian Linux, published on 19 May 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, sockmap: Prevent lock inversion deadlock in map delete elem
syzkaller started using corpuses where a BPF tracing program deletes elements from a sockmap/sockhash map. Because BPF tracing programs can be invoked from any interrupt context, locks taken during a map_delete_elem operation must be hardirq-safe. Otherwise a deadlock due to lock inversion is possible, as reported by lockdep:
CPU0 CPU1 ---- ---- lock(&htab->buckets[i].lock); local_irq_disable(); lock(&host->lock); lock(&htab->buckets[i].lock); <Interrupt> lock(&host->lock);
Locks in sockmap are hardirq-unsafe by design. We expects elements to be deleted from sockmap/sockhash only in task (normal) context with interrupts enabled, or in softirq context.
Detect when map_delete_elem operation is invoked from a context which is _not_ hardirq-unsafe, that is interrupts are disabled, and bail out with an error.
Note that map updates are not affected by this issue. BPF verifier does not allow updating sockmap/sockhash from a BPF tracing program today.
Weakness: CWE-667
Which versions are affected by CVE-2024-35895?
It affects 2 products.
Products include Debian Debian Linux, Linux kernel.
How do I fix CVE-2024-35895?
Apply the vendor's patch.
Is CVE-2024-35895 being exploited?
There is no known exploitation of CVE-2024-35895 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as BELL-CVE-2024-35895, DEBIAN-CVE-2024-35895, GHSA-37c3-qm4g-jf9g, ROOT-OS-UBUNTU-2404-CVE-2024-35895, UBUNTU-CVE-2024-35895.