forked from luck/tmp_suning_uos_patched
9017201e8d
commit bc55cfd5718c7c23e5524582e9fa70b4d10f2433 upstream.
syzbot caught a potential deadlock between the PCM
runtime->buffer_mutex and the mm->mmap_lock. It was brought by the
recent fix to cover the racy read/write and other ioctls, and in that
commit, I overlooked a (hopefully only) corner case that may take the
revert lock, namely, the OSS mmap. The OSS mmap operation
exceptionally allows to re-configure the parameters inside the OSS
mmap syscall, where mm->mmap_mutex is already held. Meanwhile, the
copy_from/to_user calls at read/write operations also take the
mm->mmap_lock internally, hence it may lead to a AB/BA deadlock.
A similar problem was already seen in the past and we fixed it with a
refcount (in commit
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| .. | ||
| oss | ||
| seq | ||
| compress_offload.c | ||
| control_compat.c | ||
| control.c | ||
| ctljack.c | ||
| device.c | ||
| hrtimer.c | ||
| hwdep_compat.c | ||
| hwdep.c | ||
| info_oss.c | ||
| info.c | ||
| init.c | ||
| isadma.c | ||
| jack.c | ||
| Kconfig | ||
| Makefile | ||
| memalloc.c | ||
| memory.c | ||
| misc.c | ||
| pcm_compat.c | ||
| pcm_dmaengine.c | ||
| pcm_drm_eld.c | ||
| pcm_iec958.c | ||
| pcm_lib.c | ||
| pcm_local.h | ||
| pcm_memory.c | ||
| pcm_misc.c | ||
| pcm_native.c | ||
| pcm_param_trace.h | ||
| pcm_timer.c | ||
| pcm_trace.h | ||
| pcm.c | ||
| rawmidi_compat.c | ||
| rawmidi.c | ||
| seq_device.c | ||
| sgbuf.c | ||
| sound_oss.c | ||
| sound.c | ||
| timer_compat.c | ||
| timer.c | ||
| vmaster.c | ||