Re: [patch] Btrfs: dereferencing free'd memory in panic message

[Josef Bacik <jbacik@fusionio.com>]

On 06/22/2012 03:14 AM, Dan Carpenter wrote:
> We free "node" and then dereference it in the panic message on the next
> line.  I considered moving the kfree() after the panic given that panic
> can return under certain configurations, but in the end I decided it
> doesn't matter if we leak a bit after a panic.
>
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
>
> diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
> index 790f492..c50d80a 100644
> --- a/fs/btrfs/relocation.c
> +++ b/fs/btrfs/relocation.c
> @@ -1239,7 +1239,6 @@ static int __must_check __add_reloc_root(struct btrfs_root *root)
>   			      node->bytenr, &node->rb_node);
>   	spin_unlock(&rc->reloc_root_tree.lock);
>   	if (rb_node) {
> -		kfree(node);
>   		btrfs_panic(root->fs_info, -EEXIST, "Duplicate root found "
>   			    "for start=%llu while inserting into relocation "
>   			    "tree\n", node->bytenr);

Except btrfs_panic can not panic the box if it's mounted to not panic on 
errors, so we still need to do the kfree afterwards.  Thanks,

Josef