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net: fix bridge multicast packet checksum validation

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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: 9afd85c9e4 ("net: Export IGMP/MLD message validation code")
Reported-by: Álvaro Fernández Rojas <noltari@gmail.com>
Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Linus Lüssing 2016-02-24 04:21:42 +01:00 committed by David S. Miller
parent a4690afeb0
commit 9b368814b3
1 changed files with 20 additions and 2 deletions
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22
net/core/skbuff.c
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@ -2947,6 +2947,24 @@ int skb_append_pagefrags(struct sk_buff *skb, struct page *page,
}
EXPORT_SYMBOL_GPL(skb_append_pagefrags);
/**
* skb_push_rcsum - push skb and update receive checksum
* @skb: buffer to update
* @len: length of data pulled
*
* This function performs an skb_push on the packet and updates
* the CHECKSUM_COMPLETE checksum. It should be used on
* receive path processing instead of skb_push unless you know
* that the checksum difference is zero (e.g., a valid IP header)
* or you are setting ip_summed to CHECKSUM_NONE.
*/
static unsigned char *skb_push_rcsum(struct sk_buff *skb, unsigned len)
{
skb_push(skb, len);
skb_postpush_rcsum(skb, skb->data, len);
return skb->data;
}
/**
* skb_pull_rcsum - pull skb and update receive checksum
* @skb: buffer to update
@ -4084,9 +4102,9 @@ struct sk_buff *skb_checksum_trimmed(struct sk_buff *skb,
if (!pskb_may_pull(skb_chk, offset))
goto err;
__skb_pull(skb_chk, offset);
skb_pull_rcsum(skb_chk, offset);
ret = skb_chkf(skb_chk);
__skb_push(skb_chk, offset);
skb_push_rcsum(skb_chk, offset);
if (ret)
goto err;