Subject: Re: [PATCH net] bonding: fix ICMPv6 header handling when receiving IPv6 messages

From: Jay Vosburgh <[email-masked]>
Date: Tue, 01 Nov 2022 11:12:43 +0100

Hangbin Liu <[email-masked]> wrote:

>Some drivers, like bnx2x, will call ipv6_gro_receive() and set skb
>IPv6 transport header before bond_handle_frame(). But some other drivers,
>like be2net, will not call ipv6_gro_receive() and skb transport header
>is not set properly. Thus we can't use icmp6_hdr(skb) to get the icmp6
>header directly when dealing with IPv6 messages.

	I don't understand this explanation, as ipv6_gro_receive() isn't
called directly by the device drivers, but from within the GRO
processing, e.g., by dev_gro_receive().

	Could you explain how the call paths actually differ?  

	-J

>Fix this by checking the skb length manually and getting icmp6 header based
>on the IPv6 header offset.
>
>Reported-by: Liang Li <[email-masked]>
>Fixes: 4e24be018eb9 ("bonding: add new parameter ns_targets")
>Signed-off-by: Hangbin Liu <[email-masked]>
>---
> drivers/net/bonding/bond_main.c | 15 +++++++++++++--
> 1 file changed, 13 insertions(+), 2 deletions(-)
>
>diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
>index e84c49bf4d0c..08b5f512f5fb 100644
>--- a/drivers/net/bonding/bond_main.c
>+++ b/drivers/net/bonding/bond_main.c
>@@ -3231,12 +3231,23 @@ static int bond_na_rcv(const struct sk_buff *skb, struct bonding *bond,
> 		       struct slave *slave)
> {
> 	struct slave *curr_active_slave, *curr_arp_slave;
>-	struct icmp6hdr *hdr = icmp6_hdr(skb);
>+	const struct icmp6hdr *icmp6_hdr;
> 	struct in6_addr *saddr, *daddr;
>+	const struct ipv6hdr *hdr;
>+	u16 pkt_len;
>+
>+	/* Check if the length is enough manually as we can't use pskb_may_pull */
>+	hdr = ipv6_hdr(skb);
>+	pkt_len = ntohs(hdr->payload_len);
>+	if (hdr->nexthdr != NEXTHDR_ICMP || pkt_len < sizeof(*icmp6_hdr) ||
>+	    skb_headlen(skb) < sizeof(*hdr) + pkt_len)
>+		goto out;
>+
>+	icmp6_hdr = (const struct icmp6hdr *)(skb->data + sizeof(*hdr));
> 
> 	if (skb->pkt_type == PACKET_OTHERHOST ||
> 	    skb->pkt_type == PACKET_LOOPBACK ||
>-	    hdr->icmp6_type != NDISC_NEIGHBOUR_ADVERTISEMENT)
>+	    icmp6_hdr->icmp6_type != NDISC_NEIGHBOUR_ADVERTISEMENT)
> 		goto out;
> 
> 	saddr = &ipv6_hdr(skb)->saddr;
>-- 
>2.38.1
>

---
	-Jay Vosburgh, [email-masked]