From: gaoxingwang gaoxingwang1@huawei.com
stable inclusion from stable-v6.6.33 commit 11dd90c11ad0aa60311214bedb8cbed530e4e609 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IAD6H2
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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[ Upstream commit 1cd354fe1e4864eeaff62f66ee513080ec946f20 ]
In IPv6, ipv6_rcv_core will parse the hop-by-hop type extension header and increase skb->transport_header by one extension header length. But if there are more other extension headers like fragment header at this time, the skb->transport_header points to the second extension header, not the transport layer header or the first extension header.
This will result in the start and nexthdrp variable not pointing to the same position in ipv6frag_thdr_trunced, and ipv6_skip_exthdr returning incorrect offset and frag_off.Sometimes,the length of the last sharded packet is smaller than the calculated incorrect offset, resulting in packet loss. We can use network header to offset and calculate the correct position to solve this problem.
Fixes: 9d9e937b1c8b (ipv6/netfilter: Discard first fragment not including all headers) Signed-off-by: Gao Xingwang gaoxingwang1@huawei.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Wang Hai wanghai38@huawei.com --- net/ipv6/reassembly.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c index 5ebc47da1000..2af98edef87e 100644 --- a/net/ipv6/reassembly.c +++ b/net/ipv6/reassembly.c @@ -369,7 +369,7 @@ static int ipv6_frag_rcv(struct sk_buff *skb) * the source of the fragment, with the Pointer field set to zero. */ nexthdr = hdr->nexthdr; - if (ipv6frag_thdr_truncated(skb, skb_transport_offset(skb), &nexthdr)) { + if (ipv6frag_thdr_truncated(skb, skb_network_offset(skb) + sizeof(struct ipv6hdr), &nexthdr)) { __IP6_INC_STATS(net, __in6_dev_get_safely(skb->dev), IPSTATS_MIB_INHDRERRORS); icmpv6_param_prob(skb, ICMPV6_HDR_INCOMP, 0);