CVE-2023-53281

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

drivers: staging: rtl8723bs: Fix locking in _rtw_join_timeout_handler()

Commit 041879b12ddb (drivers: staging: rtl8192bs: Fix deadlock in rtw_joinbss_event_prehandle()) besides fixing the deadlock also modified rtw_join_timeout_handler() to use spin[un]lock_irq() instead of spin_[un]lock_bh().

rtw_join_timeout_handler() calls rtw_do_join() which takes pmlmepriv->scanned_queue.lock using spin[un]lock_bh(). This spin_unlock_bh() call re-enables softirqs which triggers an oops in kernel/softirq.c: __local_bh_enable_ip() when it calls lockdep_assert_irqs_enabled():

[ 244.506087] WARNING: CPU: 2 PID: 0 at kernel/softirq.c:376 __local_bh_enable_ip+0xa6/0x100 … [ 244.509022] Call Trace: [ 244.509048] [ 244.509100] _rtw_join_timeout_handler+0x134/0x170 [r8723bs] [ 244.509468] ? __pfx__rtw_join_timeout_handler+0x10/0x10 [r8723bs] [ 244.509772] ? __pfx__rtw_join_timeout_handler+0x10/0x10 [r8723bs] [ 244.510076] call_timer_fn+0x95/0x2a0 [ 244.510200] __run_timers.part.0+0x1da/0x2d0

This oops is causd by the switch to spin_[un]lock_irq() which disables the IRQs for the entire duration of _rtw_join_timeout_handler().

Disabling the IRQs is not necessary since all code taking this lock runs from either user contexts or from softirqs, switch back to spin_[un]lock_bh() to fix this.

Affected Software

References

• https://git.kernel.org/stable/c/209850f17717a3b5cc558578bef5631ac7045539
• https://git.kernel.org/stable/c/215792eda008f6a1e7ed9d77fa20d582d22bb114
• https://git.kernel.org/stable/c/2a50e44a66d268ee5db3d177f1fdc1503dbce6e7
• https://git.kernel.org/stable/c/4ab1bace1dd3875371b481ef4301c4671bddea22
• https://git.kernel.org/stable/c/dc327e87c6d9bfd9ee08e76396b3c0ba848ec554