[PATCH AUTOSEL 6.5 16/34] ALSA: hda: Fix possible null-ptr-deref when assigning a stream

Sasha Levin
2023-11-07T15:53:04Z

From: Cezary Rojewski <cezary.rojewski@intel.com>

[ Upstream commit f93dc90c2e8ed664985e366aa6459ac83cdab236 ]

While AudioDSP drivers assign streams exclusively of HOST or LINK type,
nothing blocks a user to attempt to assign a COUPLED stream. As
supplied substream instance may be a stub, what is the case when
code-loading, such scenario ends with null-ptr-deref.

Signed-off-by: Cezary Rojewski <cezary.rojewski@intel.com>
Link: https://lore.kernel.org/r/20231006102857.749143-2-cezary.rojewski@intel.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
sound/hda/hdac_stream.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/sound/hda/hdac_stream.c b/sound/hda/hdac_stream.c
index 2633a4bb1d85d..214a0680524b0 100644
--- a/sound/hda/hdac_stream.c
+++ b/sound/hda/hdac_stream.c
@@ -354,8 +354,10 @@ struct hdac_stream *snd_hdac_stream_assign(struct hdac_bus *bus,
struct hdac_stream *res = NULL;

/* make a non-zero unique key for the substream */
- int key = (substream->pcm->device << 16) | (substream->number << 2) |
- (substream->stream + 1);
+ int key = (substream->number << 2) | (substream->stream + 1);
+
+ if (substream->pcm)
+ key |= (substream->pcm->device << 16);

spin_lock_irq(&bus->reg_lock);
list_for_each_entry(azx_dev, &bus->stream_list, list) {
--
2.42.0