ALSA: hda: fix a possible null-pointer dereference due to data race in snd_hdac_regmap_sync()
[ Upstream commit 1f4a08fed4
]
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
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5ed4dbc137
Коммит
8703b26387
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@ -597,10 +597,9 @@ EXPORT_SYMBOL_GPL(snd_hdac_regmap_update_raw_once);
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*/
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void snd_hdac_regmap_sync(struct hdac_device *codec)
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{
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if (codec->regmap) {
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mutex_lock(&codec->regmap_lock);
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mutex_lock(&codec->regmap_lock);
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if (codec->regmap)
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regcache_sync(codec->regmap);
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mutex_unlock(&codec->regmap_lock);
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}
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mutex_unlock(&codec->regmap_lock);
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}
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EXPORT_SYMBOL_GPL(snd_hdac_regmap_sync);
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