From: Christian Brauner <christian.brauner@ubuntu.com>
To: Christoph Hellwig <hch@lst.de>
Cc: davem@davemloft.net, kuba@kernel.org, ast@kernel.org,
daniel@iogearbox.net, netdev@vger.kernel.org,
bpf@vger.kernel.org, Rodrigo Madera <rodrigo.madera@gmail.com>
Subject: Re: [PATCH net] net/bpfilter: initialize pos in __bpfilter_process_sockopt
Date: Thu, 30 Jul 2020 18:13:03 +0200 [thread overview]
Message-ID: <20200730161303.erzgrhqsgc77d4ny@wittgenstein> (raw)
In-Reply-To: <20200730160900.187157-1-hch@lst.de>
On Thu, Jul 30, 2020 at 06:09:00PM +0200, Christoph Hellwig wrote:
> __bpfilter_process_sockopt never initialized the pos variable passed to
> the pipe write. This has been mostly harmless in the past as pipes
> ignore the offset, but the switch to kernel_write no verified the
s/no/now/
> position, which can lead to a failure depending on the exact stack
> initialization patter. Initialize the variable to zero to make
s/patter/pattern/
> rw_verify_area happy.
>
> Fixes: 6955a76fbcd5 ("bpfilter: switch to kernel_write")
> Reported-by: Christian Brauner <christian.brauner@ubuntu.com>
> Reported-by: Rodrigo Madera <rodrigo.madera@gmail.com>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Tested-by: Rodrigo Madera <rodrigo.madera@gmail.com>
> ---
Thanks for tracking this down, Christoph! This fixes the logging issue
for me.
Tested-by: Christian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: Christian Brauner <christian.brauner@ubuntu.com>
> net/bpfilter/bpfilter_kern.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/bpfilter/bpfilter_kern.c b/net/bpfilter/bpfilter_kern.c
> index 1905e01c3aa9a7..4494ea6056cdb8 100644
> --- a/net/bpfilter/bpfilter_kern.c
> +++ b/net/bpfilter/bpfilter_kern.c
> @@ -39,7 +39,7 @@ static int __bpfilter_process_sockopt(struct sock *sk, int optname,
> {
> struct mbox_request req;
> struct mbox_reply reply;
> - loff_t pos;
> + loff_t pos = 0;
> ssize_t n;
> int ret = -EFAULT;
>
> --
> 2.27.0
>
next prev parent reply other threads:[~2020-07-30 16:13 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-30 16:09 [PATCH net] net/bpfilter: initialize pos in __bpfilter_process_sockopt Christoph Hellwig
2020-07-30 16:13 ` Christian Brauner [this message]
2020-07-31 0:07 ` Daniel Borkmann
2020-08-01 19:48 ` Alexei Starovoitov
2020-08-03 14:56 ` Daniel Borkmann
2020-08-03 15:36 ` Rodrigo Madera
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