linux-kernel - [PATCH] opl3: Fix a possible sleep-in-atomic bug in snd_opl3_find

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Date:   Mon,  9 Oct 2017 10:35:27 +0800
From:   Jia-Ju Bai <baijiaju1990@....com>
To:     perex@...ex.cz, tiwai@...e.com, o-takashi@...amocchi.jp,
        elfring@...rs.sourceforge.net, fabf@...net.be
Cc:     alsa-devel@...a-project.org, linux-kernel@...r.kernel.org,
        Jia-Ju Bai <baijiaju1990@....com>
Subject: [PATCH] opl3: Fix a possible sleep-in-atomic bug in snd_opl3_find_patch

The driver may sleep under a spinlock, and the function call path is:
snd_opl3_note_on (acquire the spinlock)
  snd_opl3_find_patch
    kzalloc(GFP_KERNEL) --> may sleep

To fix it, GFP_KERNEL is replaced with GFP_ATOMIC.
This bug is found by my static analysis tool and my code review.

Signed-off-by: Jia-Ju Bai <baijiaju1990@....com>
---
 sound/drivers/opl3/opl3_synth.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sound/drivers/opl3/opl3_synth.c b/sound/drivers/opl3/opl3_synth.c
index ddcc1a3..2e1cb2b 100644
--- a/sound/drivers/opl3/opl3_synth.c
+++ b/sound/drivers/opl3/opl3_synth.c
@@ -325,7 +325,7 @@ struct fm_patch *snd_opl3_find_patch(struct snd_opl3 *opl3, int prog, int bank,
 	if (!create_patch)
 		return NULL;
 
-	patch = kzalloc(sizeof(*patch), GFP_KERNEL);
+	patch = kzalloc(sizeof(*patch), GFP_ATOMIC);
 	if (!patch)
 		return NULL;
 	patch->prog = prog;
-- 
1.7.9.5