[PATCH 4.14 077/124] ext4: missing !bh check in ext4_xattr_inode_write()

Greg Kroah-Hartman
2018-11-19T16:51:46Z

From: Vasily Averin <vvs@virtuozzo.com>

commit eb6984fa4ce2837dcb1f66720a600f31b0bb3739 upstream.

According to Ted Ts'o ext4_getblk() called in ext4_xattr_inode_write()
should not return bh = NULL

The only time that bh could be NULL, then, would be in the case of
something really going wrong; a programming error elsewhere (perhaps a
wild pointer dereference) or I/O error causing on-disk file system
corruption (although that would be highly unlikely given that we had
*just* allocated the blocks and so the metadata blocks in question
probably would still be in the cache).

Fixes: e50e5129f384 ("ext4: xattr-in-inode support")
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org # 4.13
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/ext4/xattr.c | 6 ++++++
1 file changed, 6 insertions(+)

--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -1387,6 +1387,12 @@ retry:
bh = ext4_getblk(handle, ea_inode, block, 0);
if (IS_ERR(bh))
return PTR_ERR(bh);
+ if (!bh) {
+ WARN_ON_ONCE(1);
+ EXT4_ERROR_INODE(ea_inode,
+ "ext4_getblk() return bh = NULL");
+ return -EFSCORRUPTED;
+ }
ret = ext4_journal_get_write_access(handle, bh);
if (ret)
goto out;