From ff175d57f057f77d2d3031d674c2af9167a4af02 Mon Sep 17 00:00:00 2001 From: Jesper Juhl Date: Sat, 25 Dec 2010 21:22:30 +0000 Subject: [PATCH] btrfs: Don't pass NULL ptr to func that may deref it. Hi, In fs/btrfs/inode.c::fixup_tree_root_location() we have this code: ... if (!path) { err = -ENOMEM; goto out; } ... out: btrfs_free_path(path); return err; btrfs_free_path() passes its argument on to other functions and some of them end up dereferencing the pointer. In the code above that pointer is clearly NULL, so btrfs_free_path() will eventually cause a NULL dereference. There are many ways to cut this cake (fix the bug). The one I chose was to make btrfs_free_path() deal gracefully with NULL pointers. If you disagree, feel free to come up with an alternative patch. Signed-off-by: Jesper Juhl Signed-off-by: Chris Mason --- fs/btrfs/ctree.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index 9ac171599258..99599f1c1554 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -105,6 +105,8 @@ noinline void btrfs_clear_path_blocking(struct btrfs_path *p, /* this also releases the path */ void btrfs_free_path(struct btrfs_path *p) { + if (!p) + return; btrfs_release_path(NULL, p); kmem_cache_free(btrfs_path_cachep, p); }