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Message-Id: <20110411164812.8f84f995.akpm@linux-foundation.org>
Date: Mon, 11 Apr 2011 16:48:12 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: vitalyb@...enet.dn.ua
Cc: bugzilla-daemon@...zilla.kernel.org,
bugme-daemon@...zilla.kernel.org, netdev@...r.kernel.org
Subject: Re: [Bugme-new] [Bug 32872] New: LLC PDU is dropped if skb is not
linear
(switched to email. Please respond via emailed reply-to-all, not via the
bugzilla web interface).
On Fri, 8 Apr 2011 09:52:34 GMT
bugzilla-daemon@...zilla.kernel.org wrote:
> https://bugzilla.kernel.org/show_bug.cgi?id=32872
>
> Summary: LLC PDU is dropped if skb is not linear
> Product: Networking
> Version: 2.5
> Kernel Version: 2.6.32
> Platform: All
> OS/Version: Linux
> Tree: Mainline
> Status: NEW
> Severity: normal
> Priority: P1
> Component: Other
> AssignedTo: acme@...stprotocols.net
> ReportedBy: vitalyb@...enet.dn.ua
> Regression: No
>
>
> If skb consists of several fragments this check fails
> net/llc/llc_input.c:
> =============================================
> llc_fixup_skb()
> ...
> pdu = (struct llc_pdu_un *)skb->data;
> ...
> __be16 pdulen = eth_hdr(skb)->h_proto;
> s32 data_size = ntohs(pdulen) - llc_len;
>
> if (data_size < 0 ||
> ((skb_tail_pointer(skb) -
> (u8 *)pdu) - llc_len) < data_size)
> return 0;
> =============================================
>
> and packet is silently dropped.
>
> This breaks GVRP protocol if received packet is large ( > 512 bytes on my
> system) and contains a Leave All message. Since Leave All is missed,
> corresponding JoinIns are not sent and switch unregisters VLANs from port.
>
> Attached patch seems to resolve this issue, but I don't know if it's a correct
> solution.
--- linux-2.6.32.36/net/llc/llc_input.c.orig 2009-12-03 05:51:21.000000000 +0200
+++ linux-2.6.32.36/net/llc/llc_input.c 2011-04-08 08:57:29.000000000 +0300
@@ -105,6 +105,11 @@
if (unlikely(!pskb_may_pull(skb, sizeof(*pdu))))
return 0;
+ if (skb->data_len != 0){
+ if (unlikely(skb_linearize(skb)))
+ return 0;
+ }
+
pdu = (struct llc_pdu_un *)skb->data;
if ((pdu->ctrl_1 & LLC_PDU_TYPE_MASK) == LLC_PDU_TYPE_U)
llc_len = 1;
2.6.32 is a pretty old kernel - we'll need to verify if current kernels
have the same problem.
Please don't send patches via bugzilla - it causes lots of problems
with our usual patch management and review processes. It's preferred
that patches be sent via email as per Documentation/SubmittingPatches,
and that they include a Signed-off-by:, as described in that file.
Thanks.
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