From: Chengfeng Ye cyeaa@connect.ust.hk

[ Upstream commit a0d21bb3279476c777434c40d969ea88ca64f9aa ]

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 cyeaa@connect.ust.hk Link: https://lore.kernel.org/r/20211024104611.9919-1-cyeaa@connect.ust.hk Signed-off-by: Takashi Iwai tiwai@suse.de Signed-off-by: Sasha Levin sashal@kernel.org --- 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 36c27c8323601..2e27cd3427c87 100644 --- a/sound/isa/gus/gus_dma.c +++ b/sound/isa/gus/gus_dma.c @@ -141,6 +141,8 @@ 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