Re: [patch] Btrfs: dereferencing free'd memory in panic message
From: Josef Bacik <hidden>
Date: 2012-06-22 13:32:40
Also in:
kernel-janitors
On 06/22/2012 09:30 AM, Dan Carpenter wrote:
On Fri, Jun 22, 2012 at 09:09:04AM -0400, Josef Bacik wrote:quoted
On 06/22/2012 03:14 AM, Dan Carpenter wrote:quoted
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 <redacted>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,Right. I mentioned that in my change log, but I figured a one time memory leak was the least of our concerns in that case. I will resend. This should probably return -EEXIST here as well yes?
Ah sorry I thought you were talking about BUG_ON() not actually stopping the box in some cases. But yes I'd like to not leak anyway and return -EEXIST. Thanks, Josef