From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?q?Linus=20L=C3=BCssing?= Subject: [PATCH] net: fix bridge multicast packet checksum validation Date: Mon, 15 Feb 2016 03:07:06 +0100 Message-ID: <1455502026-23144-1-git-send-email-linus.luessing@c0d3.blue> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Cc: Tom Herbert , bridge@lists.linux-foundation.org, linux-kernel@vger.kernel.org, "Steinar H . Gunderson" , "David S . Miller" To: netdev@vger.kernel.org Return-path: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: bridge-bounces@lists.linux-foundation.org Errors-To: bridge-bounces@lists.linux-foundation.org List-Id: netdev.vger.kernel.org We need to update the skb->csum after pulling the skb, otherwise checksum validation will fail. This fixes multicast packet loss for bridges and splats like the following: [...] [ 43.986968] eth0: hw csum failure [ 43.990344] CPU: 3 PID: 0 Comm: swapper/3 Not tainted 4.4.0 #2 [ 43.996193] Hardware name: BCM2709 [ 43.999647] [<800204e0>] (unwind_backtrace) from [<8001cf14>] (show_st= ack+0x10/0x14) [ 44.007432] [<8001cf14>] (show_stack) from [<801ab614>] (dump_stack+0x= 80/0x90) [ 44.014695] [<801ab614>] (dump_stack) from [<802e4548>] (__skb_checksu= m_complete+0x6c/0xac) [ 44.023090] [<802e4548>] (__skb_checksum_complete) from [<803a055c>] (= ipv6_mc_validate_checksum+0x104/0x178) [ 44.032959] [<803a055c>] (ipv6_mc_validate_checksum) from [<802e111c>]= (skb_checksum_trimmed+0x130/0x188) [ 44.042565] [<802e111c>] (skb_checksum_trimmed) from [<803a06e8>] (ipv= 6_mc_check_mld+0x118/0x338) [ 44.051501] [<803a06e8>] (ipv6_mc_check_mld) from [<803b2c98>] (br_mul= ticast_rcv+0x5dc/0xd00) [ 44.060077] [<803b2c98>] (br_multicast_rcv) from [<803aa510>] (br_hand= le_frame_finish+0xac/0x51c) [...] Fixes: 9afd85c9e455 ("net: Export IGMP/MLD message validation code") Reported-by: =C3=81lvaro Fern=C3=A1ndez Rojas Signed-off-by: Linus L=C3=BCssing --- Steinar, can you check whether this fixes the bridge issues you reported = on bugzilla #99081? Not quite sure whether it is the same as yours as you do not seem to have any such call traces. I am not super happy with how this patch looks, but there is no "skb_push= _rcsum" available and skb_pull_rcsum() seems non-reversible as is. Alternative su= ggestions always welcome. net/core/skbuff.c | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 5bf88f5..6c34ef6 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -4076,6 +4076,11 @@ struct sk_buff *skb_checksum_trimmed(struct sk_buf= f *skb, struct sk_buff *skb_chk; unsigned int offset =3D skb_transport_offset(skb); __sum16 ret; + int ip_summed; + int csum_valid; + int csum_level; + int csum_bad; + __wsum csum; =20 skb_chk =3D skb_checksum_maybe_trim(skb, transport_len); if (!skb_chk) @@ -4084,10 +4089,22 @@ struct sk_buff *skb_checksum_trimmed(struct sk_bu= ff *skb, if (!pskb_may_pull(skb_chk, offset)) goto err; =20 - __skb_pull(skb_chk, offset); + ip_summed =3D skb->ip_summed; + csum_valid =3D skb->csum_valid; + csum_level =3D skb->csum_level; + csum_bad =3D skb->csum_bad; + csum =3D skb->csum; + + skb_pull_rcsum(skb_chk, offset); ret =3D skb_chkf(skb_chk); __skb_push(skb_chk, offset); =20 + skb->ip_summed =3D ip_summed; + skb->csum_valid =3D csum_valid; + skb->csum_level =3D csum_level; + skb->csum_bad =3D csum_bad; + skb->csum =3D csum; + if (ret) goto err; =20 --=20 1.7.10.4