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Date:   Thu, 15 Jun 2023 22:23:27 -0700
From:   Jakub Kicinski <kuba@kernel.org>
To:     Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Cc:     David Howells <dhowells@redhat.com>, netdev@vger.kernel.org,
        syzbot+d8486855ef44506fd675@syzkaller.appspotmail.com,
        David Ahern <dsahern@kernel.org>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Paolo Abeni <pabeni@redhat.com>, Jens Axboe <axboe@kernel.dk>,
        Matthew Wilcox <willy@infradead.org>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH net-next] ip, ip6: Fix splice to raw and ping sockets
Message-ID: <20230615222327.15e85c55@kernel.org>
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On Wed, 14 Jun 2023 09:04:16 +0100 David Howells wrote:
> Splicing to SOCK_RAW sockets may set MSG_SPLICE_PAGES, but in such a case,
> __ip_append_data() will call skb_splice_from_iter() to access the 'from'
> data, assuming it to point to a msghdr struct with an iter, instead of
> using the provided getfrag function to access it.
> 
> In the case of raw_sendmsg(), however, this is not the case and 'from' will
> point to a raw_frag_vec struct and raw_getfrag() will be the frag-getting
> function.  A similar issue may occur with rawv6_sendmsg().
> 
> Fix this by ignoring MSG_SPLICE_PAGES if getfrag != ip_generic_getfrag as
> ip_generic_getfrag() expects "from" to be a msghdr*, but the other getfrags
> don't.  Note that this will prevent MSG_SPLICE_PAGES from being effective
> for udplite.
> 
> This likely affects ping sockets too.  udplite looks like it should be okay
> as it expects "from" to be a msghdr.

Willem, looks good?