This is a note to let you know that I've just added the patch titled ALSA: pcm: Check for null pointer of pointer substream before dereferencing it to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: alsa-pcm-check-for-null-pointer-of-pointer-substream.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 7278d05e016f1cf46d73780ccd76f0784723aa42 Author: Colin Ian King <colin.king@xxxxxxxxx> Date: Sun Apr 24 21:59:45 2022 +0100 ALSA: pcm: Check for null pointer of pointer substream before dereferencing it [ 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@xxxxxxxxx> Link: https://lore.kernel.org/r/20220424205945.1372247-1-colin.i.king@xxxxxxxxx Signed-off-by: Takashi Iwai <tiwai@xxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/sound/core/pcm_memory.c b/sound/core/pcm_memory.c index f1fb856ff4ac..f1470590239e 100644 --- a/sound/core/pcm_memory.c +++ b/sound/core/pcm_memory.c @@ -446,7 +446,6 @@ 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)) @@ -455,6 +454,8 @@ 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);