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authorTuo Li <islituo@gmail.com>2023-07-03 11:10:16 +0800
committerTakashi Iwai <tiwai@suse.de>2023-07-03 10:08:12 +0200
commit1f4a08fed450db87fbb5ff5105354158bdbe1a22 (patch)
treef079a1a65d8a0629fdf4a54c8192a047a082bbd1 /sound
parent73f1c75d5e6bd8ce2a887ef493a66ad1b16ed704 (diff)
ALSA: hda: fix a possible null-pointer dereference due to data race in snd_hdac_regmap_sync()
The variable codec->regmap is often protected by the lock codec->regmap_lock when is accessed. However, it is accessed without holding the lock when is accessed in snd_hdac_regmap_sync(): if (codec->regmap) In my opinion, this may be a harmful race, because if codec->regmap is set to NULL right after the condition is checked, a null-pointer dereference can occur in the called function regcache_sync(): map->lock(map->lock_arg); --> Line 360 in drivers/base/regmap/regcache.c To fix this possible null-pointer dereference caused by data race, the mutex_lock coverage is extended to protect the if statement as well as the function call to regcache_sync(). [ Note: the lack of the regmap_lock itself is harmless for the current codec driver implementations, as snd_hdac_regmap_sync() is only for PM runtime resume that is prohibited during the codec probe. But the change makes the whole code more consistent, so it's merged as is -- tiwai ] Reported-by: BassCheck <bass@buaa.edu.cn> Signed-off-by: Tuo Li <islituo@gmail.com> Link: https://lore.kernel.org/r/20230703031016.1184711-1-islituo@gmail.com Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound')
-rw-r--r--sound/hda/hdac_regmap.c7
1 files changed, 3 insertions, 4 deletions
diff --git a/sound/hda/hdac_regmap.c b/sound/hda/hdac_regmap.c
index f258cb3a6895..9b1bcabd8414 100644
--- a/sound/hda/hdac_regmap.c
+++ b/sound/hda/hdac_regmap.c
@@ -596,10 +596,9 @@ EXPORT_SYMBOL_GPL(snd_hdac_regmap_update_raw_once);
*/
void snd_hdac_regmap_sync(struct hdac_device *codec)
{
- if (codec->regmap) {
- mutex_lock(&codec->regmap_lock);
+ mutex_lock(&codec->regmap_lock);
+ if (codec->regmap)
regcache_sync(codec->regmap);
- mutex_unlock(&codec->regmap_lock);
- }
+ mutex_unlock(&codec->regmap_lock);
}
EXPORT_SYMBOL_GPL(snd_hdac_regmap_sync);