[PATCH 4.17 16/18] xfs: dont call xfs_da_shrink_inode with NULL bp

Greg Kroah-Hartman
2018-08-07T18:53:27Z

From: Eric Sandeen <sandeen@sandeen.net>

commit bb3d48dcf86a97dc25fe9fc2c11938e19cb4399a upstream.

xfs_attr3_leaf_create may have errored out before instantiating a buffer,
for example if the blkno is out of range. In that case there is no work
to do to remove it, and in fact xfs_da_shrink_inode will lead to an oops
if we try.

This also seems to fix a flaw where the original error from
xfs_attr3_leaf_create gets overwritten in the cleanup case, and it
removes a pointless assignment to bp which isn't used after this.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=199969
Reported-by: Xu, Wen <wen.xu@gatech.edu>
Tested-by: Xu, Wen <wen.xu@gatech.edu>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/xfs/libxfs/xfs_attr_leaf.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

--- a/fs/xfs/libxfs/xfs_attr_leaf.c
+++ b/fs/xfs/libxfs/xfs_attr_leaf.c
@@ -803,9 +803,8 @@ xfs_attr_shortform_to_leaf(
ASSERT(blkno == 0);
error = xfs_attr3_leaf_create(args, blkno, &bp);
if (error) {
- error = xfs_da_shrink_inode(args, 0, bp);
- bp = NULL;
- if (error)
+ /* xfs_attr3_leaf_create may not have instantiated a block */
+ if (bp && (xfs_da_shrink_inode(args, 0, bp) != 0))
goto out;
xfs_idata_realloc(dp, size, XFS_ATTR_FORK); /* try to put */
memcpy(ifp->if_u1.if_data, tmpbuffer, size); /* it back */