[PATCH] btrfs: sysfs: Use scnprintf() for avoiding potential buffer overflow

[Takashi Iwai <tiwai@suse.de>]

Since snprintf() returns the would-be-output size instead of the
actual output size, the succeeding calls may go beyond the given
buffer limit.  Fix it by replacing with scnprintf().

Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 fs/btrfs/sysfs.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 93cf76118a04..d3dc069789a5 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -310,12 +310,12 @@ static ssize_t supported_checksums_show(struct kobject *kobj,
 		 * This "trick" only works as long as 'enum btrfs_csum_type' has
 		 * no holes in it
 		 */
-		ret += snprintf(buf + ret, PAGE_SIZE - ret, "%s%s",
+		ret += scnprintf(buf + ret, PAGE_SIZE - ret, "%s%s",
 				(i == 0 ? "" : " "), btrfs_super_csum_name(i));
 
 	}
 
-	ret += snprintf(buf + ret, PAGE_SIZE - ret, "\n");
+	ret += scnprintf(buf + ret, PAGE_SIZE - ret, "\n");
 	return ret;
 }
 BTRFS_ATTR(static_feature, supported_checksums, supported_checksums_show);
@@ -992,7 +992,7 @@ char *btrfs_printable_features(enum btrfs_feature_set set, u64 flags)
 			continue;
 
 		name = btrfs_feature_attrs[set][i].kobj_attr.attr.name;
-		len += snprintf(str + len, bufsize - len, "%s%s",
+		len += scnprintf(str + len, bufsize - len, "%s%s",
 				len ? "," : "", name);
 	}
 
-- 
2.16.4