CVE-2022-48848 tracing/osnoise: Do not unregister events twice
A double unregister bug in the Linux kernel osnoise tracer causes a kernel warning and potential instability when stopping tracing.
- 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-2022-48848?
CVE-2022-48848 is a high-severity denial of service vulnerability in Linux kernel, published on 16 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:
tracing/osnoise: Do not unregister events twice
Nicolas reported that using:
# trace-cmd record -e all -M 10 -p osnoise --poll
Resulted in the following kernel warning:
------------[ cut here ]------------ WARNING: CPU: 0 PID: 1217 at kernel/tracepoint.c:404 tracepoint_probe_unregister+0x280/0x370 [...] CPU: 0 PID: 1217 Comm: trace-cmd Not tainted 5.17.0-rc6-next-20220307-nico+ #19 RIP: 0010:tracepoint_probe_unregister+0x280/0x370 [...] CR2: 00007ff919b29497 CR3: 0000000109da4005 CR4: 0000000000170ef0 Call Trace: <TASK> osnoise_workload_stop+0x36/0x90 tracing_set_tracer+0x108/0x260 tracing_set_trace_write+0x94/0xd0 ? __check_object_size.part.0+0x10a/0x150 ? selinux_file_permission+0x104/0x150 vfs_write+0xb5/0x290 ksys_write+0x5f/0xe0 do_syscall_64+0x3b/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7ff919a18127 [...] ---[ end trace 0000000000000000 ]---
The warning complains about an attempt to unregister an unregistered tracepoint.
This happens on trace-cmd because it first stops tracing, and then switches the tracer to nop. Which is equivalent to:
# cd /sys/kernel/tracing/ # echo osnoise > current_tracer # echo 0 > tracing_on # echo nop > current_tracer
The osnoise tracer stops the workload when no trace instance is actually collecting data. This can be caused both by disabling tracing or disabling the tracer itself.
To avoid unregistering events twice, use the existing trace_osnoise_callback_enabled variable to check if the events (and the workload) are actually active before trying to deactivate them.
Which versions are affected by CVE-2022-48848?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2022-48848?
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-2022-48848 being exploited?
There is no known exploitation of CVE-2022-48848 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as DEBIAN-CVE-2022-48848, GHSA-6gcc-c84m-wqv4, UBUNTU-CVE-2022-48848.