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Subject[PATCH 5.15 074/279] ALSA: gus: fix null pointer dereference on pointer block
Date
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 a1c770d826dda..6d664dd8dde0b 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
--
2.33.0


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