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authorRobb Glasser <[email protected]>2017-12-05 09:16:55 -0800
committerTakashi Iwai <[email protected]>2017-12-05 23:28:08 +0100
commit362bca57f5d78220f8b5907b875961af9436e229 (patch)
tree744d83b54aa7820babaa178e52336159b024b161
parentf429e7e494afaded76e62c6f98211a635aa03098 (diff)
ALSA: pcm: prevent UAF in snd_pcm_info
When the device descriptor is closed, the `substream->runtime` pointer is freed. But another thread may be in the ioctl handler, case SNDRV_CTL_IOCTL_PCM_INFO. This case calls snd_pcm_info_user() which calls snd_pcm_info() which accesses the now freed `substream->runtime`. Note: this fixes CVE-2017-0861 Signed-off-by: Robb Glasser <[email protected]> Signed-off-by: Nick Desaulniers <[email protected]> Cc: <[email protected]> Signed-off-by: Takashi Iwai <[email protected]>
-rw-r--r--sound/core/pcm.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/sound/core/pcm.c b/sound/core/pcm.c
index 9070f277f8db..09ee8c6b9f75 100644
--- a/sound/core/pcm.c
+++ b/sound/core/pcm.c
@@ -153,7 +153,9 @@ static int snd_pcm_control_ioctl(struct snd_card *card,
err = -ENXIO;
goto _error;
}
+ mutex_lock(&pcm->open_mutex);
err = snd_pcm_info_user(substream, info);
+ mutex_unlock(&pcm->open_mutex);
_error:
mutex_unlock(&register_mutex);
return err;