From: Takashi Iwai <tiwai@xxxxxxx>
commit 8e537d5dec34cac746dd6abf6a83e5de3aa471fc upstream.
The recent refactoring of mmap handling caused Oops on some devices
that don't use the standard memory allocations. This patch addresses
it by allowing snd_dma_buffer_mmap() helper to receive the NULL
pointer dmab argument (and return an error appropriately).
Fixes: a202bd1ad86d ("ALSA: core: Move mmap handler into memalloc ops")
Cc: <stable@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20211107163911.13534-1-tiwai@xxxxxxx
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
sound/core/memalloc.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
--- a/sound/core/memalloc.c
+++ b/sound/core/memalloc.c
@@ -135,8 +135,11 @@ EXPORT_SYMBOL(snd_dma_free_pages);
int snd_dma_buffer_mmap(struct snd_dma_buffer *dmab,
struct vm_area_struct *area)
{
- const struct snd_malloc_ops *ops = snd_dma_get_ops(dmab);
+ const struct snd_malloc_ops *ops;
+ if (!dmab)
+ return -ENOENT;
+ ops = snd_dma_get_ops(dmab);
if (ops && ops->mmap)
return ops->mmap(dmab, area);
else
