From mboxrd@z Thu Jan 1 00:00:00 1970 From: Josef Bacik Date: Fri, 22 Jun 2012 13:09:04 +0000 Subject: Re: [patch] Btrfs: dereferencing free'd memory in panic message Message-Id: <4FE46E70.8070702@fusionio.com> List-Id: References: <20120622071433.GA27618@elgon.mountain> In-Reply-To: <20120622071433.GA27618@elgon.mountain> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Dan Carpenter Cc: "Chris L. Mason" , "linux-btrfs@vger.kernel.org" , "kernel-janitors@vger.kernel.org" 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 > > 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