[PATCH net] ipv6: sr: fix TLVs not being copied using setsockopt

Function ipv6_push_rthdr4 allows to add an IPv6 Segment Routing Header
to a socket through setsockopt, but the current implementation doesn't
copy possible TLVs at the end of the SRH (i.e., the following branch
if (sr_has_hmac(sr_phdr)) will never be taken as no HMAC TLV is copied).

This commit adds a memcpy in case TLVs have been appended to the SRH.

Fixes: a149e7c7ce812561f0fdc7a86ddc42f294e5eb3e ("ipv6: sr: add
support for SRH injection through setsockopt")
Acked-by: David Lebrun <redacted>
Signed-off-by: Mathieu Xhonneux <redacted>
---
 net/ipv6/exthdrs.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/net/ipv6/exthdrs.c b/net/ipv6/exthdrs.c
index 83bd75713535..bc68eb661970 100644
--- a/net/ipv6/exthdrs.c
+++ b/net/ipv6/exthdrs.c

@@ -925,6 +925,15 @@ static void ipv6_push_rthdr4(struct sk_buff *skb, u8 *proto,
        sr_phdr->segments[0] = **addr_p;
        *addr_p = &sr_ihdr->segments[sr_ihdr->segments_left];

+       if (sr_ihdr->hdrlen > hops * 2) {
+               int tlvs_offset, tlvs_length;
+
+               tlvs_offset = (1 + hops * 2) << 3;
+               tlvs_length = (sr_ihdr->hdrlen - hops * 2) << 3;
+               memcpy((char *)sr_phdr + tlvs_offset,
+                      (char *)sr_ihdr + tlvs_offset, tlvs_length);
+       }
+
 #ifdef CONFIG_IPV6_SEG6_HMAC
        if (sr_has_hmac(sr_phdr)) {
                struct net *net = NULL;
--

2.15.1