linux-kernel - Re: [PATCHv3] net: fix bridge multicast packet checksum validation

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Date:	Thu, 25 Feb 2016 16:19:39 -0500 (EST)
From:	David Miller <davem@...emloft.net>
To:	linus.luessing@...3.blue
Cc:	netdev@...r.kernel.org, stephen@...workplumber.org,
	bridge@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
	sgunderson@...foot.com, noltari@...il.com, tom@...bertland.com
Subject: Re: [PATCHv3] net: fix bridge multicast packet checksum validation

From: Linus Lüssing <linus.luessing@...3.blue>
Date: Wed, 24 Feb 2016 04:21:42 +0100

> We need to update the skb->csum after pulling the skb, otherwise
> an unnecessary checksum (re)computation can ocure for IGMP/MLD packets
> in the bridge code. Additionally this fixes the following splats for
> network devices / bridge ports with support for and enabled RX checksum
> offloading:
> 
> [...]
> [   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_stack+0x10/0x14)
> [   44.007432] [<8001cf14>] (show_stack) from [<801ab614>] (dump_stack+0x80/0x90)
> [   44.014695] [<801ab614>] (dump_stack) from [<802e4548>] (__skb_checksum_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>] (ipv6_mc_check_mld+0x118/0x338)
> [   44.051501] [<803a06e8>] (ipv6_mc_check_mld) from [<803b2c98>] (br_multicast_rcv+0x5dc/0xd00)
> [   44.060077] [<803b2c98>] (br_multicast_rcv) from [<803aa510>] (br_handle_frame_finish+0xac/0x51c)
> [...]
> 
> Fixes: 9afd85c9e455 ("net: Export IGMP/MLD message validation code")
> Reported-by: Álvaro Fernández Rojas <noltari@...il.com>
> Signed-off-by: Linus Lüssing <linus.luessing@...3.blue>

Applied and queued up for -stable, thanks!