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Re: [PATCH] xfsprogs: fix use after free in inode_item_done()

To: Eric Sandeen <sandeen@xxxxxxxxxx>
Subject: Re: [PATCH] xfsprogs: fix use after free in inode_item_done()
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Tue, 4 Mar 2014 09:36:17 +1100
Cc: xfs-oss <xfs@xxxxxxxxxxx>
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <5314E912.9080708@xxxxxxxxxx>
References: <5314E912.9080708@xxxxxxxxxx>
User-agent: Mutt/1.5.21 (2010-09-15)
On Mon, Mar 03, 2014 at 02:41:54PM -0600, Eric Sandeen wrote:
> Commit "3a19fb7 libxfs: stop caching inode structures"
> introduced a use after free.
> 
> libxfs_iput() already does the check for ip->i_itemp, and a
> kmem_zone_free() if it's present, and then frees the ip pointer.
> Re-checking ip->i_itemp after the libxfs_iput call will access
> the freed ip pointer, as will setting ip_>i_itemp to NULL.
> 
> Simply remove the offending code to fix this up.

which leaves the rest of the ili_done: code looking a little
strange.

can you convert that now to be:

ili_done:
        if (iip->ili_lock_flags) {
                iip->ili_lock_flags = 0;
                return;
        }
        /* free the inode */
        libxfs_iput(ip, 0);
}

Cheers,

Dave.
-- 
Dave Chinner
david@xxxxxxxxxxxxx

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