diff options
| author | Daniel Rosenberg <drosen@google.com> | 2017-10-31 16:55:26 -0700 |
|---|---|---|
| committer | Moyster <oysterized@gmail.com> | 2018-05-16 13:59:09 +0200 |
| commit | d6a5b2bb21682c4b2c634af20ba3d1210ac834de (patch) | |
| tree | 30c73e5af798560f13293558888711e4cc758eeb /include/sound | |
| parent | ad781944055a2b79c3cfb6c5231ab2d5fd0c9a6b (diff) | |
ANDROID: sound: rawmidi: Hold lock around realloc
The SNDRV_RAWMIDI_STREAM_{OUTPUT,INPUT} ioctls may reallocate
runtime->buffer while other kernel threads are accessing it. If the
underlying krealloc() call frees the original buffer, then this can turn
into a use-after-free.
Most of these accesses happen while the thread is holding runtime->lock,
and can be fixed by just holding the same lock while replacing
runtime->buffer, however we can't hold this spinlock while
snd_rawmidi_kernel_{read1,write1} are copying to/from userspace. We
need to add and acquire a new mutex to prevent this from happening
concurrently with reallocation. We hold this mutex during the entire
reallocation process, to also prevent multiple concurrent reallocations
leading to a double-free.
Signed-off-by: Daniel Rosenberg <drosen@google.com>
bug: 64315347
Change-Id: I05764d4f1a38f373eb7c0ac1c98607ee5ff0eded
Diffstat (limited to 'include/sound')
| -rw-r--r-- | include/sound/rawmidi.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/sound/rawmidi.h b/include/sound/rawmidi.h index adf088515..76ef2a447 100644 --- a/include/sound/rawmidi.h +++ b/include/sound/rawmidi.h @@ -77,6 +77,7 @@ struct snd_rawmidi_runtime { size_t xruns; /* over/underruns counter */ /* misc */ spinlock_t lock; + struct mutex realloc_mutex; wait_queue_head_t sleep; /* event handler (new bytes, input only) */ void (*event)(struct snd_rawmidi_substream *substream); |