[PATCH 5.17 290/772] ALSA: pcm: Check for null pointer of pointer substream before dereferencing it

Greg Kroah-Hartman
2022-06-07T20:59:41Z

From: Colin Ian King <colin.i.king@gmail.com>

[ Upstream commit 011b559be832194f992f73d6c0d5485f5925a10b ]

Pointer substream is being dereferenced on the assignment of pointer card
before substream is being null checked with the macro PCM_RUNTIME_CHECK.
Although PCM_RUNTIME_CHECK calls BUG_ON, it still is useful to perform the
the pointer check before card is assigned.

Fixes: d4cfb30fce03 ("ALSA: pcm: Set per-card upper limit of PCM buffer allocations")
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Link: https://lore.kernel.org/r/20220424205945.1372247-1-colin.i.king@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
sound/core/pcm_memory.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/sound/core/pcm_memory.c b/sound/core/pcm_memory.c
index 8848d2f3160d..b8296b6eb2c1 100644
--- a/sound/core/pcm_memory.c
+++ b/sound/core/pcm_memory.c
@@ -453,7 +453,6 @@ EXPORT_SYMBOL(snd_pcm_lib_malloc_pages);
*/
int snd_pcm_lib_free_pages(struct snd_pcm_substream *substream)
{
- struct snd_card *card = substream->pcm->card;
struct snd_pcm_runtime *runtime;

if (PCM_RUNTIME_CHECK(substream))
@@ -462,6 +461,8 @@ int snd_pcm_lib_free_pages(struct snd_pcm_substream *substream)
if (runtime->dma_area == NULL)
return 0;
if (runtime->dma_buffer_p != &substream->dma_buffer) {
+ struct snd_card *card = substream->pcm->card;
+
/* it's a newly allocated buffer. release it now. */
do_free_pages(card, runtime->dma_buffer_p);
kfree(runtime->dma_buffer_p);
--
2.35.1