[PATCH 3.18 04/24] hfsplus: prevent btree data loss on root split

From: Greg Kroah-Hartman
Date: Mon Nov 26 2018 - 05:52:51 EST

3.18-stable review patch. If anyone has any objections, please let me know.


[ Upstream commit 0a3021d4f5295aa073c7bf5c5e4de60a2e292578 ]

Creating, renaming or deleting a file may cause catalog corruption and
data loss. This bug is randomly triggered by xfstests generic/027, but
here is a faster reproducer:

truncate -s 50M fs.iso
mkfs.hfsplus fs.iso
mount fs.iso /mnt
while [ $i -le 150 ]; do
touch /mnt/$i &>/dev/null
while [ $i -le 150 ]; do
mv /mnt/$i /mnt/$(perl -e "print $i x82") &>/dev/null
umount /mnt
fsck.hfsplus -n fs.iso

The bug is triggered whenever hfs_brec_update_parent() needs to split the
root node. The height of the btree is not increased, which leaves the new
node orphaned and its records lost.

Link: http://lkml.kernel.org/r/26d882184fc43043a810114258f45277752186c7.1535682461.git.ernesto.mnd.fernandez@xxxxxxxxx
Signed-off-by: Ernesto A. FernÃndez <ernesto.mnd.fernandez@xxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
fs/hfsplus/brec.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/fs/hfsplus/brec.c b/fs/hfsplus/brec.c
index 754fdf8c6356..1002a0c08319 100644
--- a/fs/hfsplus/brec.c
+++ b/fs/hfsplus/brec.c
@@ -427,6 +427,10 @@ skip:
if (new_node) {
__be32 cnid;

+ if (!new_node->parent) {
+ hfs_btree_inc_height(tree);
+ new_node->parent = tree->root;
+ }
fd->bnode = hfs_bnode_find(tree, new_node->parent);
/* create index key and entry */
hfs_bnode_read_key(new_node, fd->search_key, 14);