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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Kangjie Lu <kjlu@umn.edu>,
        Takashi Iwai <tiwai@suse.de>, Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.4 102/168] ALSA: sb8: add a check for request_region
Date:   Wed, 24 Apr 2019 19:09:06 +0200
Message-Id: <20190424170929.671852037@linuxfoundation.org>
In-Reply-To: <20190424170923.452349382@linuxfoundation.org>
References: <20190424170923.452349382@linuxfoundation.org>
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[ Upstream commit dcd0feac9bab901d5739de51b3f69840851f8919 ]

In case request_region fails, the fix returns an error code to
avoid NULL pointer dereference.

Signed-off-by: Kangjie Lu <kjlu@umn.edu>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 sound/isa/sb/sb8.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/sound/isa/sb/sb8.c b/sound/isa/sb/sb8.c
index b8e2391c33ff..0c7fe1418447 100644
--- a/sound/isa/sb/sb8.c
+++ b/sound/isa/sb/sb8.c
@@ -111,6 +111,10 @@ static int snd_sb8_probe(struct device *pdev, unsigned int dev)
 
 	/* block the 0x388 port to avoid PnP conflicts */
 	acard->fm_res = request_region(0x388, 4, "SoundBlaster FM");
+	if (!acard->fm_res) {
+		err = -EBUSY;
+		goto _err;
+	}
 
 	if (port[dev] != SNDRV_AUTO_PORT) {
 		if ((err = snd_sbdsp_create(card, port[dev], irq[dev],
-- 
2.19.1