CVE-2022-49450 rxrpc: Fix listen() setting the bar too high for the prealloc rings
A local attacker can cause a kernel crash by setting a specific backlog value on an AF_RXRPC socket, leading to a null pointer dereference.
- 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-2022-49450?
CVE-2022-49450 is a medium-severity vulnerability in Linux kernel, published on 26 Feb 2025. 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:
rxrpc: Fix listen() setting the bar too high for the prealloc rings
AF_RXRPC's listen() handler lets you set the backlog up to 32 (if you bump up the sysctl), but whilst the preallocation circular buffers have 32 slots in them, one of them has to be a dead slot because we're using CIRC_CNT().
This means that listen(rxrpc_sock, 32) will cause an oops when the socket is closed because rxrpc_service_prealloc_one() allocated one too many calls and rxrpc_discard_prealloc() won't then be able to get rid of them because it'll think the ring is empty. rxrpc_release_calls_on_socket() then tries to abort them, but oopses because call->peer isn't yet set.
Fix this by setting the maximum backlog to RXRPC_BACKLOG_MAX - 1 to match the ring capacity.
BUG: kernel NULL pointer dereference, address: 0000000000000086 ... RIP: 0010:rxrpc_send_abort_packet+0x73/0x240 [rxrpc] Call Trace: <TASK> ? __wake_up_common_lock+0x7a/0x90 ? rxrpc_notify_socket+0x8e/0x140 [rxrpc] ? rxrpc_abort_call+0x4c/0x60 [rxrpc] rxrpc_release_calls_on_socket+0x107/0x1a0 [rxrpc] rxrpc_release+0xc9/0x1c0 [rxrpc] __sock_release+0x37/0xa0 sock_close+0x11/0x20 __fput+0x89/0x240 task_work_run+0x59/0x90 do_exit+0x319/0xaa0
Weakness: CWE-476
Which versions are affected by CVE-2022-49450?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2022-49450?
Apply the vendor's patch.
Is CVE-2022-49450 being exploited?
There is no known exploitation of CVE-2022-49450 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as DEBIAN-CVE-2022-49450, GHSA-fcw8-q8jr-pq38, UBUNTU-CVE-2022-49450.