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Date:   Tue, 28 Jul 2020 01:25:12 -0400
From:   Peilin Ye <yepeilin.cs@gmail.com>
To:     Song Liu <song@kernel.org>
Cc:     =?iso-8859-1?Q?Bj=F6rn_T=F6pel?= <bjorn.topel@intel.com>,
        Magnus Karlsson <magnus.karlsson@intel.com>,
        Jonathan Lemon <jonathan.lemon@gmail.com>,
        Dan Carpenter <dan.carpenter@oracle.com>,
        Arnd Bergmann <arnd@arndb.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Jesper Dangaard Brouer <hawk@kernel.org>,
        John Fastabend <john.fastabend@gmail.com>,
        Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
        Andrii Nakryiko <andriin@fb.com>,
        KP Singh <kpsingh@chromium.org>,
        linux-kernel-mentees@lists.linuxfoundation.org,
        Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>
Subject: Re: [Linux-kernel-mentees] [PATCH net] xdp: Prevent kernel-infoleak
 in xsk_getsockopt()
Message-ID: <20200728052512.GA404005@PWN>
References: <20200728022859.381819-1-yepeilin.cs@gmail.com>
 <CAPhsuW7L6KWAM55=oLgQ2MtoJOB9i4mwZHOVF+KJj7W5ht_+YQ@mail.gmail.com>
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On Mon, Jul 27, 2020 at 10:07:20PM -0700, Song Liu wrote:
> On Mon, Jul 27, 2020 at 7:30 PM Peilin Ye <yepeilin.cs@gmail.com> wrote:
> >
> > xsk_getsockopt() is copying uninitialized stack memory to userspace when
> > `extra_stats` is `false`. Fix it by initializing `stats` with memset().
> >
> > Cc: stable@vger.kernel.org
> 
> 8aa5a33578e9 is not in stable branches yet, so we don't need to Cc stable.
> 
> > Fixes: 8aa5a33578e9 ("xsk: Add new statistics")
> > Suggested-by: Dan Carpenter <dan.carpenter@oracle.com>
> > Signed-off-by: Peilin Ye <yepeilin.cs@gmail.com>
> > ---
> >  net/xdp/xsk.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
> > index 26e3bba8c204..acf001908a0d 100644
> > --- a/net/xdp/xsk.c
> > +++ b/net/xdp/xsk.c
> > @@ -844,6 +844,8 @@ static int xsk_getsockopt(struct socket *sock, int level, int optname,
> >                 bool extra_stats = true;
> >                 size_t stats_size;
> >
> > +               memset(&stats, 0, sizeof(stats));
> > +
> 
> xsk.c doesn't include linux/string.h directly, so using memset may break
> build for some config combinations. We can probably just use
> 
> struct xdp_statistics stats = {};

I see. I will send v2 soon. Thank you for reviewing the patch!

Peilin Ye