Commit d057c036 authored Oct 30, 2018 by Ernesto A. Fernández Committed by Linus Torvalds Oct 31, 2018

hfs: prevent btree data loss on root split

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>

parent 19a9d0f1

fs/hfs/brec.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -425,6 +425,10 @@ 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);