hfs: do not free node before using
authorPan Bian <bianpan2016@163.com>
Fri, 30 Nov 2018 22:09:14 +0000 (14:09 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 30 Nov 2018 22:56:14 +0000 (14:56 -0800)
hfs_bmap_free() frees the node via hfs_bnode_put(node).  However, it
then reads node->this when dumping error message on an error path, which
may result in a use-after-free bug.  This patch frees the node only when
it is never again used.

Link: http://lkml.kernel.org/r/1542963889-128825-1-git-send-email-bianpan2016@163.com
Fixes: a1185ffa2fc ("HFS rewrite")
Signed-off-by: Pan Bian <bianpan2016@163.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Joe Perches <joe@perches.com>
Cc: Ernesto A. Fernandez <ernesto.mnd.fernandez@gmail.com>
Cc: Viacheslav Dubeyko <slava@dubeyko.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fs/hfs/btree.c

index 98b96ffb95ed3d71dbf598b9aadc1e4363ce68da..19017d2961734fd7701aa1ac31c6a94d8a65c71b 100644 (file)
@@ -338,13 +338,14 @@ void hfs_bmap_free(struct hfs_bnode *node)
 
                nidx -= len * 8;
                i = node->next;
-               hfs_bnode_put(node);
                if (!i) {
                        /* panic */;
                        pr_crit("unable to free bnode %u. bmap not found!\n",
                                node->this);
+                       hfs_bnode_put(node);
                        return;
                }
+               hfs_bnode_put(node);
                node = hfs_bnode_find(tree, i);
                if (IS_ERR(node))
                        return;