From a0d21bb3279476c777434c40d969ea88ca64f9aa Mon Sep 17 00:00:00 2001 From: Chengfeng Ye Date: Sun, 24 Oct 2021 03:46:11 -0700 Subject: [PATCH] ALSA: gus: fix null pointer dereference on pointer block The pointer block return from snd_gf1_dma_next_block could be null, so there is a potential null pointer dereference issue. Fix this by adding a null check before dereference. Signed-off-by: Chengfeng Ye Link: https://lore.kernel.org/r/20211024104611.9919-1-cyeaa@connect.ust.hk Signed-off-by: Takashi Iwai --- sound/isa/gus/gus_dma.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/sound/isa/gus/gus_dma.c b/sound/isa/gus/gus_dma.c index a1c770d826dd..6d664dd8dde0 100644 --- a/sound/isa/gus/gus_dma.c +++ b/sound/isa/gus/gus_dma.c @@ -126,6 +126,8 @@ static void snd_gf1_dma_interrupt(struct snd_gus_card * gus) } block = snd_gf1_dma_next_block(gus); spin_unlock(&gus->dma_lock); + if (!block) + return; snd_gf1_dma_program(gus, block->addr, block->buf_addr, block->count, (unsigned short) block->cmd); kfree(block); #if 0