Commit ff175d57 authored Dec 25, 2010 by Jesper Juhl Committed by Chris Mason Jan 16, 2011

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 <jj@chaosbits.net>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

parent 20b45077

fs/btrfs/ctree.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -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);
		}