[PATCH 4.16 072/272] Btrfs: fix NULL pointer dereference in log_dir_items

Greg Kroah-Hartman
2018-05-28T11:07:20Z

From: Liu Bo <bo.liu@linux.alibaba.com>

[ Upstream commit 80c0b4210a963e31529e15bf90519708ec947596 ]

0, 1 and <0 can be returned by btrfs_next_leaf(), and when <0 is
returned, path->nodes[0] could be NULL, log_dir_items lacks such a
check for <0 and we may run into a null pointer dereference panic.

Fixes: e02119d5a7b4 ("Btrfs: Add a write ahead tree log to optimize synchronous operations")
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/btrfs/tree-log.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -3548,8 +3548,11 @@ static noinline int log_dir_items(struct
* from this directory and from this transaction
*/
ret = btrfs_next_leaf(root, path);
- if (ret == 1) {
- last_offset = (u64)-1;
+ if (ret) {
+ if (ret == 1)
+ last_offset = (u64)-1;
+ else
+ err = ret;
goto done;
}
btrfs_item_key_to_cpu(path->nodes[0], &tmp, path->slots[0]);