In the Linux kernel, the following vulnerability has been resolved: ASoC: fsl_xcvr: Revert fix missing lock in fsl_xcvr_mode_put() This reverts commit f51424872760 ("ASoC: fsl_xcvr: fix missing lock in fsl_xcvr_mode_put()"). The original patch attempted to acquire the card-controls_rwsem lock in fsl_xcvr_mode_put(). However, this function is called from the upper ALSA core function snd_ctl_elem_write(), which already holds the write lock on controls_rwsem for the whole put operation.

So there is no need to simply hold the lock for fsl_xcvr_activate_ctl() again. Acquiring the read lock while holding the write lock in the same thread results in a deadlock and a hung task, as reported by Alexander Stein.