From: Pan Bian <bianpan2016@xxxxxxx> Subject: hfs: do not free node before using 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@xxxxxxx Fixes: a1185ffa2fc ("HFS rewrite") Signed-off-by: Pan Bian <bianpan2016@xxxxxxx> Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Joe Perches <joe@xxxxxxxxxxx> Cc: Ernesto A. Fernandez <ernesto.mnd.fernandez@xxxxxxxxx> Cc: Viacheslav Dubeyko <slava@xxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/hfs/btree.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/fs/hfs/btree.c~hfs-do-not-free-node-before-using +++ a/fs/hfs/btree.c @@ -338,13 +338,14 @@ void hfs_bmap_free(struct hfs_bnode *nod 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; _
