CVE-2024-26731 bpf, sockmap: Fix NULL pointer dereference in sk_psock_verdict_data_ready()
A race condition in the Linux kernel BPF sockmap can cause a NULL pointer dereference, leading to a system crash.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2024-26731?
CVE-2024-26731 is a medium-severity vulnerability in Linux kernel, published on 3 Apr 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
bpf, sockmap: Fix NULL pointer dereference in sk_psock_verdict_data_ready()
syzbot reported the following NULL pointer dereference issue [1]:
BUG: kernel NULL pointer dereference, address: 0000000000000000 [...] RIP: 0010:0x0 [...] Call Trace: <TASK> sk_psock_verdict_data_ready+0x232/0x340 net/core/skmsg.c:1230 unix_stream_sendmsg+0x9b4/0x1230 net/unix/af_unix.c:2293 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg+0x221/0x270 net/socket.c:745 ____sys_sendmsg+0x525/0x7d0 net/socket.c:2584 ___sys_sendmsg net/socket.c:2638 [inline] __sys_sendmsg+0x2b0/0x3a0 net/socket.c:2667 do_syscall_64+0xf9/0x240 entry_SYSCALL_64_after_hwframe+0x6f/0x77
If sk_psock_verdict_data_ready() and sk_psock_stop_verdict() are called concurrently, psock->saved_data_ready can be NULL, causing the above issue.
This patch fixes this issue by calling the appropriate data ready function using the sk_psock_data_ready() helper and protecting it from concurrency with sk->sk_callback_lock.
Weakness: CWE-476
Which versions are affected by CVE-2024-26731?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-26731?
Apply the vendor's patch.
Is CVE-2024-26731 being exploited?
There is no known exploitation of CVE-2024-26731 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2024-26731, DEBIAN-CVE-2024-26731, GHSA-x96q-4pr8-5qm2, UBUNTU-CVE-2024-26731.