Jesper Juhl
2010-Dec-25 21:22 UTC
[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 <jj@chaosbits.net>
---
ctree.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 9ac1715..99599f1 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);
}
--
Jesper Juhl <jj@chaosbits.net> http://www.chaosbits.net/
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