[PATCH] ext4: missing !bh check in ext4_xattr_inode_write()

[Vasily Averin]

ext4_getblk() called with map_flags=0 can return NULL,
it can lead to oops on bh dereferemce

Fixes e50e5129f384 ("ext4: xattr-in-inode support")
Cc: stable@xxxxxxxxxx # 4.13

Signed-off-by: Vasily Averin <vvs@xxxxxxxxxxxxx>
---
 fs/ext4/xattr.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index 0b9688683526..6dc6c70828f0 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -1384,6 +1384,8 @@ static int ext4_xattr_inode_write(handle_t *handle, struct inode *ea_inode,
 		bh = ext4_getblk(handle, ea_inode, block, 0);
 		if (IS_ERR(bh))
 			return PTR_ERR(bh);
+		if (!bh)
+			return -ENOMEM;
 		ret = ext4_journal_get_write_access(handle, bh);
 		if (ret)
 			goto out;
-- 
2.17.1