[PATCH] fs: ext4: Fix dereferencing the null pointer 'ptr'

[Mikhail Ilin]

 If memory allocation fails on line 780, then 'fail' will be
 jumped to and 'ptr' will be null, causing it to be dereferenced it on line
 855. Thus, before using 'ptr[i]' one must make sure that the 'ptr' pointer
 is not NULL.

Fixes: 934b14f2bb30 ("ext4: free allocations by parse_path()")
Signed-off-by: Mikhail Ilin <ilin.mikhail.ol at gmail.com>
---
 fs/ext4/ext4_common.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/fs/ext4/ext4_common.c b/fs/ext4/ext4_common.c
index 1185cb2c04..3cdd1a04a9 100644
--- a/fs/ext4/ext4_common.c
+++ b/fs/ext4/ext4_common.c
@@ -851,10 +851,12 @@ end:
 fail:
 	free(depth_dirname);
 	free(parse_dirname);
-	for (i = 0; i < depth; i++) {
-		if (!ptr[i])
-			break;
-		free(ptr[i]);
+	if (ptr) {
+		for (i = 0; i < depth; i++) {
+			if (!ptr[i])
+				break;
+			free(ptr[i]);
+		}
 	}
 	free(ptr);
 	free(parent_inode);
-- 
2.17.1