[alsa-devel] [patch] ASoC: soc: snprintf() doesn't return negative

[Dan Carpenter]

In user space snprintf() returns negative on errors but the kernel
version only returns positives.  It could potentially return sizes
larger than the size of the buffer so we should check for that.

Signed-off-by: Dan Carpenter <error27 at gmail.com>

diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c
index 8751efd..8da307b 100644
--- a/sound/soc/soc-core.c
+++ b/sound/soc/soc-core.c
@@ -284,8 +284,10 @@ static ssize_t codec_list_read_file(struct file *file, char __user *user_buf,
 		ret += snprintf(buf + ret, PAGE_SIZE - ret, "%s\n",
 				codec->name);
 
-	if (ret >= 0)
-		ret = simple_read_from_buffer(user_buf, count, ppos, buf, ret);
+	if (ret > PAGE_SIZE)
+		ret = PAGE_SIZE;
+
+	ret = simple_read_from_buffer(user_buf, count, ppos, buf, ret);
 
 	kfree(buf);
 
@@ -310,8 +312,10 @@ static ssize_t dai_list_read_file(struct file *file, char __user *user_buf,
 	list_for_each_entry(dai, &dai_list, list)
 		ret += snprintf(buf + ret, PAGE_SIZE - ret, "%s\n", dai->name);
 
-	if (ret >= 0)
-		ret = simple_read_from_buffer(user_buf, count, ppos, buf, ret);
+	if (ret > PAGE_SIZE)
+		ret = PAGE_SIZE;
+
+	ret = simple_read_from_buffer(user_buf, count, ppos, buf, ret);
 
 	kfree(buf);
 
@@ -338,8 +342,10 @@ static ssize_t platform_list_read_file(struct file *file,
 		ret += snprintf(buf + ret, PAGE_SIZE - ret, "%s\n",
 				platform->name);
 
-	if (ret >= 0)
-		ret = simple_read_from_buffer(user_buf, count, ppos, buf, ret);
+	if (ret > PAGE_SIZE)
+		ret = PAGE_SIZE;
+
+	ret = simple_read_from_buffer(user_buf, count, ppos, buf, ret);
 
 	kfree(buf);