linux-kernel - Re: [PATCH] fuse: avoid clobbering fc->release with fuse_conn

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Date:	Mon, 1 Jun 2015 14:03:02 +0200
From:	Miklos Szeredi <miklos@...redi.hu>
To:	Jeremiah Mahler <jmmahler@...il.com>
Cc:	fuse-devel <fuse-devel@...ts.sourceforge.net>,
	Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] fuse: avoid clobbering fc->release with fuse_conn_init(fc)

On Mon, Jun 1, 2015 at 3:31 AM, Jeremiah Mahler <jmmahler@...il.com> wrote:
> fuse_conn_init(fc) zeros the entire fc structure before it assigns
> specific values.  Since fc->release is set before fuse_conn_init(fc)
> is called, the value gets set to zero, which results in a NULL pointer
> deference when fc->release() is called.  Fix the problem by assigning
> fc->release after calling fuse_conn_init(fc) instead of before.

I added this fix to the original patch and force pushed to
fuse.git/for-next.  Better keep it in one so that your fix is not left
out accidentally when being backported to -stable.

Thanks,
Miklos


>
> Signed-off-by: Jeremiah Mahler <jmmahler@...il.com>
> Fixes: daccc092d1a2 ("fuse: initialize fc->release before calling it")
> ---
>  fs/fuse/inode.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
> index 01ff55d..2913db2 100644
> --- a/fs/fuse/inode.c
> +++ b/fs/fuse/inode.c
> @@ -1076,8 +1076,8 @@ static int fuse_fill_super(struct super_block *sb, void *data, int silent)
>         if (!fc)
>                 goto err_fput;
>
> -       fc->release = fuse_free_conn;
>         fuse_conn_init(fc);
> +       fc->release = fuse_free_conn;
>
>         fud = fuse_dev_alloc(fc);
>         if (!fud)
> --
> 2.1.4
>
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