[alsa-devel] [PATCH] ALSA: pcm: prevent UAF in snd_pcm_info
From: Robb Glasser rglasser@google.com
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`.
Signed-off-by: Robb Glasser rglasser@google.com Signed-off-by: Nick Desaulniers ndesaulniers@google.com --- sound/core/pcm.c | 2 ++ 1 file changed, 2 insertions(+)
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(®ister_mutex); return err;
+ stable
On Tue, Dec 5, 2017 at 9:16 AM, Nick Desaulniers ndesaulniers@google.com wrote:
From: Robb Glasser rglasser@google.com
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`.
Signed-off-by: Robb Glasser rglasser@google.com Signed-off-by: Nick Desaulniers ndesaulniers@google.com
sound/core/pcm.c | 2 ++ 1 file changed, 2 insertions(+)
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(®ister_mutex); return err;-- 2.15.0.531.g2ccb3012c9-goog
On Tue, Dec 05, 2017 at 09:19:32AM -0800, Nick Desaulniers wrote:
- stable
On Tue, Dec 5, 2017 at 9:16 AM, Nick Desaulniers ndesaulniers@google.com wrote:
From: Robb Glasser rglasser@google.com
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`.
Signed-off-by: Robb Glasser rglasser@google.com Signed-off-by: Nick Desaulniers ndesaulniers@google.com
sound/core/pcm.c | 2 ++ 1 file changed, 2 insertions(+)
<formletter>
This is not the correct way to submit patches for inclusion in the stable kernel tree. Please read: https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html for how to do this properly.
</formletter>
On Tue, 05 Dec 2017 18:16:55 +0100, Nick Desaulniers wrote:
From: Robb Glasser rglasser@google.com
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`.
Signed-off-by: Robb Glasser rglasser@google.com Signed-off-by: Nick Desaulniers ndesaulniers@google.com
Looks reasonable. Applied with Cc to stable now.
thanks,
Takashi
sound/core/pcm.c | 2 ++ 1 file changed, 2 insertions(+)
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);-- 2.15.0.531.g2ccb3012c9-goog
On Tue, Dec 5, 2017 at 11:14 AM, Takashi Iwai tiwai@suse.de wrote:
On Tue, 05 Dec 2017 18:16:55 +0100, Nick Desaulniers wrote:
From: Robb Glasser rglasser@google.com
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`.
Signed-off-by: Robb Glasser rglasser@google.com Signed-off-by: Nick Desaulniers ndesaulniers@google.com
Looks reasonable. Applied with Cc to stable now.
FWIW, this was assigned CVE-2017-0861. (Best to get it into the commit log if possible.)
-Kees
thanks,
Takashi
sound/core/pcm.c | 2 ++ 1 file changed, 2 insertions(+)
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(®ister_mutex); return err;-- 2.15.0.531.g2ccb3012c9-goog
On Tue, 05 Dec 2017 20:29:07 +0100, Kees Cook wrote:
On Tue, Dec 5, 2017 at 11:14 AM, Takashi Iwai tiwai@suse.de wrote:
On Tue, 05 Dec 2017 18:16:55 +0100, Nick Desaulniers wrote:
From: Robb Glasser rglasser@google.com
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`.
Signed-off-by: Robb Glasser rglasser@google.com Signed-off-by: Nick Desaulniers ndesaulniers@google.com
Looks reasonable. Applied with Cc to stable now.
FWIW, this was assigned CVE-2017-0861. (Best to get it into the commit log if possible.)
OK, I updated the changelog. Thanks for information.
Takashi
participants (4)
-
Greg KH -
Kees Cook -
Nick Desaulniers -
Takashi Iwai