CVE-2024-49976

In the Linux kernel, the following vulnerability has been resolved:

tracing/timerlat: Drop interface_lock in stop_kthread()

stop_kthread() is the offline callback for trace/osnoise:online, since commit 5bfbcd1ee57b (tracing/timerlat: Add interface_lock around clearing of kthread in stop_kthread()), the following ABBA deadlock scenario is introduced:

T1 | T2 [BP] | T3 [AP] osnoise_hotplug_workfn() | work_for_cpu_fn() | cpuhp_thread_fun() | _cpu_down() | osnoise_cpu_die() mutex_lock(&interface_lock) | | stop_kthread() | cpus_write_lock() | mutex_lock(&interface_lock) cpus_read_lock() | cpuhp_kick_ap() |

As the interface_lock here in just for protecting the kthread field of the osn_var, use xchg() instead to fix this issue. Also use for_each_online_cpu() back in stop_per_cpu_kthreads() as it can take cpu_read_lock() again.

Weakness

The product does not properly acquire or release a lock on a resource, leading to unexpected resource state changes and behaviors.

Affected Software

Extended Description

Locking is a type of synchronization behavior that ensures that multiple independently-operating processes or threads do not interfere with each other when accessing the same resource. All processes/threads are expected to follow the same steps for locking. If these steps are not followed precisely - or if no locking is done at all - then another process/thread could modify the shared resource in a way that is not visible or predictable to the original process. This can lead to data or memory corruption, denial of service, etc.

Potential Mitigations

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/25.html
• https://cwe.mitre.org/data/definitions/26.html
• https://cwe.mitre.org/data/definitions/27.html

References

• https://git.kernel.org/stable/c/09cb44cc3d3df7ade2cebc939d6257a2fa8afc7a
• https://git.kernel.org/stable/c/a4a05ceffe8fad68b45de38fe2311bda619e76e2
• https://git.kernel.org/stable/c/b484a02c9cedf8703eff8f0756f94618004bd165
• https://git.kernel.org/stable/c/db8571a9a098086608c11a15856ff585789e67e8