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Date:   Thu, 12 Jul 2018 13:43:04 +0200
From:   Dominique Martinet <asmadeus@codewreck.org>
To:     Tomas Bortoli <tomasbortoli@gmail.com>
Cc:     ericvh@gmail.com, rminnich@sandia.gov, lucho@ionkov.net,
        viro@ZenIV.linux.org.uk, davem@davemloft.net,
        v9fs-developer@lists.sourceforge.net, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, syzkaller@googlegroups.com
Subject: Re: [V9fs-developer] [PATCH] p9_parse_header() validate PDU length
Message-ID: <20180712114304.GB17774@nautica>
References: <20180712110211.25535-1-tomasbortoli@gmail.com>
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Tomas Bortoli wrote on Thu, Jul 12, 2018:
> This patch adds checks to the p9_parse_header() function to
> verify that the length found within the header coincides with the actual
> length of the PDU. Furthermore, it checks that the length stays within the
> acceptable range. To do this the patch brings the actual length of the PDU
> from the different transport layers (rdma and virtio). For TCP (trans_fd.c)
> the length is not know before, so we get it from the header but we check it
> anyway that it's within the valid range.

Just a note on transports here, I totally had forgotten about trans_xen
when we discussed this earlier as it is fairly new, but it looks like it
sets the length in the fcall properly so it should work without any
change.

I however cannot test trans=xen, so if someone could either point me to
how to set that up (I couldn't find any decent documentation) or do some
very basic tests that would be great.

> Signed-off-by: Tomas Bortoli <tomasbortoli@gmail.com>
> Reported-by: syzbot+65c6b72f284a39d416b4@syzkaller.appspotmail.com

Looks good to me, as the rdma/virtio part come from my suggestion:
Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr>

> diff --git a/net/9p/trans_rdma.c b/net/9p/trans_rdma.c
> index 3d414acb7015..002badbcc9c0 100644
> --- a/net/9p/trans_rdma.c
> +++ b/net/9p/trans_rdma.c
> @@ -319,7 +319,7 @@ recv_done(struct ib_cq *cq, struct ib_wc *wc)
>  
>  	if (wc->status != IB_WC_SUCCESS)
>  		goto err_out;
> -
> +	c->rc->size = wc->byte_len;

(nitpick, I'd keep the empty line here. If you don't mind I'll add it
back in my tree; this doesn't warrant a v2)

-- 
Dominique Martinet