linux-kernel - [PATCH] sound: soc-pcm: add a check to avoid NULL pointer dereference

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Date:   Thu, 14 Mar 2019 22:44:15 -0500
From:   Kangjie Lu <kjlu@....edu>
To:     kjlu@....edu
Cc:     pakki001@....edu, Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>, alsa-devel@...a-project.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] sound: soc-pcm: add a check to avoid NULL pointer dereference

In case debugfs_create_u32 fails, the fix frees memory and returns
an error to notify callers.

Signed-off-by: Kangjie Lu <kjlu@....edu>
---
 sound/soc/soc-pcm.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/sound/soc/soc-pcm.c b/sound/soc/soc-pcm.c
index 0d5ec68a1e50..a7d88ed8ebb5 100644
--- a/sound/soc/soc-pcm.c
+++ b/sound/soc/soc-pcm.c
@@ -1231,15 +1231,21 @@ static int dpcm_be_connect(struct snd_soc_pcm_runtime *fe,
 	list_add(&dpcm->list_be, &fe->dpcm[stream].be_clients);
 	list_add(&dpcm->list_fe, &be->dpcm[stream].fe_clients);
 
-	dev_dbg(fe->dev, "connected new DPCM %s path %s %s %s\n",
-			stream ? "capture" : "playback",  fe->dai_link->name,
-			stream ? "<-" : "->", be->dai_link->name);
-
 #ifdef CONFIG_DEBUG_FS
-	if (fe->debugfs_dpcm_root)
+	if (fe->debugfs_dpcm_root) {
 		dpcm->debugfs_state = debugfs_create_u32(be->dai_link->name, 0644,
 				fe->debugfs_dpcm_root, &dpcm->state);
+		if (!dpcm->debugfs_state) {
+			kfree(dpcm);
+			return -ENOMEM;
+		}
+	}
 #endif
+
+	dev_dbg(fe->dev, "connected new DPCM %s path %s %s %s\n",
+			stream ? "capture" : "playback",  fe->dai_link->name,
+			stream ? "<-" : "->", be->dai_link->name);
+
 	return 1;
 }
 
-- 
2.17.1