CVE-2021-47392 RDMA/cma: Fix listener leak in rdma_cma_listen_on_all() failure
A local attacker can trigger a deadlock in the Linux kernel RDMA subsystem by causing a listener failure, leading to 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-2021-47392?
CVE-2021-47392 is a medium-severity denial of service vulnerability in Linux kernel, published on 21 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:
RDMA/cma: Fix listener leak in rdma_cma_listen_on_all() failure
If cma_listen_on_all() fails it leaves the per-device ID still on the listen_list but the state is not set to RDMA_CM_ADDR_BOUND.
When the cmid is eventually destroyed cma_cancel_listens() is not called due to the wrong state, however the per-device IDs are still holding the refcount preventing the ID from being destroyed, thus deadlocking:
task:rping state:D stack: 0 pid:19605 ppid: 47036 flags:0x00000084 Call Trace: __schedule+0x29a/0x780 ? free_unref_page_commit+0x9b/0x110 schedule+0x3c/0xa0 schedule_timeout+0x215/0x2b0 ? __flush_work+0x19e/0x1e0 wait_for_completion+0x8d/0xf0 _destroy_id+0x144/0x210 [rdma_cm] ucma_close_id+0x2b/0x40 [rdma_ucm] __destroy_id+0x93/0x2c0 [rdma_ucm] ? __xa_erase+0x4a/0xa0 ucma_destroy_id+0x9a/0x120 [rdma_ucm] ucma_write+0xb8/0x130 [rdma_ucm] vfs_write+0xb4/0x250 ksys_write+0xb5/0xd0 ? syscall_trace_enter.isra.19+0x123/0x190 do_syscall_64+0x33/0x40 entry_SYSCALL_64_after_hwframe+0x44/0xa9
Ensure that cma_listen_on_all() atomically unwinds its action under the lock during error.
Weakness: CWE-401
Which versions are affected by CVE-2021-47392?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2021-47392?
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-2021-47392 being exploited?
There is no known exploitation of CVE-2021-47392 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as DEBIAN-CVE-2021-47392, GHSA-3vpw-pw66-4mjh, UBUNTU-CVE-2021-47392.