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[AUTOSEL,4.9,05/17] hfs: prevent btree data loss on root split

Message ID 20181113055223.79060-5-sashal@kernel.org
State New, archived
Headers show
Series None | expand

Commit Message

Sasha Levin Nov. 13, 2018, 5:52 a.m. UTC
From: Ernesto A. Fernández <ernesto.mnd.fernandez@gmail.com>

[ Upstream commit d057c036672f33d43a5f7344acbb08cf3a8a0c09 ]

This 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.  It is not possible for this
to happen on a valid hfs filesystem because the index nodes have fixed
length keys.

For reasons I ignore, the hfs module does have support for a number of
hfsplus features.  A corrupt btree header may report variable length
keys and trigger this bug, so it's better to fix it.

Link: http://lkml.kernel.org/r/9750b1415685c4adca10766895f6d5ef12babdb0.1535682463.git.ernesto.mnd.fernandez@gmail.com
Signed-off-by: Ernesto A. Fernández <ernesto.mnd.fernandez@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/hfs/brec.c | 4 ++++
 1 file changed, 4 insertions(+)
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Patch

diff --git a/fs/hfs/brec.c b/fs/hfs/brec.c
index 2a6f3c67cb3f..2e713673df42 100644
--- a/fs/hfs/brec.c
+++ b/fs/hfs/brec.c
@@ -424,6 +424,10 @@  static int hfs_brec_update_parent(struct hfs_find_data *fd)
 	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);