From: Takashi Iwai Date: Sun, 7 Nov 2021 16:39:11 +0000 (+0100) Subject: ALSA: PCM: Fix NULL dereference at mmap checks X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=47047ae0b779bf8c2a3e18313110f2a89586e477;p=linux.git ALSA: PCM: Fix NULL dereference at mmap checks 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: Link: https://lore.kernel.org/r/20211107163911.13534-1-tiwai@suse.de Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman --- diff --git a/sound/core/memalloc.c b/sound/core/memalloc.c index c7c943c661e63..0b8a1c3eae1b4 100644 --- a/sound/core/memalloc.c +++ b/sound/core/memalloc.c @@ -176,8 +176,11 @@ EXPORT_SYMBOL_GPL(snd_devm_alloc_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