Vulnerability CVE-2024-26933
Published: 2024-05-01

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

USB: core: Fix deadlock in port "disable" sysfs attribute

The show and store callback routines for the "disable" sysfs attribute
file in port.c acquire the device lock for the port's parent hub
device. This can cause problems if another process has locked the hub
to remove it or change its configuration:

Removing the hub or changing its configuration requires the
hub interface to be removed, which requires the port device
to be removed, and device_del() waits until all outstanding
sysfs attribute callbacks for the ports have returned. The
lock can't be released until then.

But the disable_show() or disable_store() routine can't return
until after it has acquired the lock.

The resulting deadlock can be avoided by calling
sysfs_break_active_protection(). This will cause the sysfs core not
to wait for the attribute's callback routine to return, allowing the
removal to proceed. The disadvantage is that after making this call,
there is no guarantee that the hub structure won't be deallocated at
any moment. To prevent this, we have to acquire a reference to it
first by calling hub_get().

 References:
https://git.kernel.org/stable/c/9dac54f08198147f5ec0ec52fcf1bc8ac899ac05
https://git.kernel.org/stable/c/f51849833705dea5b4f9b0c8de714dd87bd6c95c
https://git.kernel.org/stable/c/4facc9421117ba9d8148c73771b213887fec77f7
https://git.kernel.org/stable/c/73d1589b91f2099e5f6534a8497b7c6b527e064e
https://git.kernel.org/stable/c/f4d1960764d8a70318b02f15203a1be2b2554ca1
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