[PATCH] ALSA: hwdep: fix NULL dereference on error path

[Guangshuo Li <lgs201920130244@gmail.com>]

snd_hwdep_new() allocates a hwdep instance first and then allocates
hwdep->dev via snd_device_alloc().

When snd_device_alloc() fails, hwdep->dev remains NULL, because
snd_device_alloc() clears *dev_p before attempting to allocate the
device object. The error path then calls snd_hwdep_free(), which
unconditionally invokes put_device(hwdep->dev).

This may lead to a NULL pointer dereference in put_device().

Fixes: 897c8882df58 ("ALSA: hwdep: Don't embed device")
Cc: stable@vger.kernel.org
Signed-off-by: Guangshuo Li <lgs201920130244@gmail.com>
---
 sound/core/hwdep.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/sound/core/hwdep.c b/sound/core/hwdep.c
index 09200df2932c..aa35bee8da6b 100644
--- a/sound/core/hwdep.c
+++ b/sound/core/hwdep.c
@@ -343,7 +343,8 @@ static void snd_hwdep_free(struct snd_hwdep *hwdep)
 		return;
 	if (hwdep->private_free)
 		hwdep->private_free(hwdep);
-	put_device(hwdep->dev);
+	if (hwdep->dev)
+		put_device(hwdep->dev);
 	kfree(hwdep);
 }
 
-- 
2.43.0