[PATCH] net: ipv4: Avoid bounds check warning

[Genjian Zhang]

From: huhai <huhai@xxxxxxxxxx>

Fix the following build warning when CONFIG_IPV6 is not set:

In function ‘fortify_memcpy_chk’,
    inlined from ‘tcp_md5_do_add’ at net/ipv4/tcp_ipv4.c:1211:2:
./include/linux/fortify-string.h:328:4: error: call to ‘__write_overflow_field’ declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror=attribute-warning]
  328 |    __write_overflow_field(p_size_field, size);
      |    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Signed-off-by: huhai <huhai@xxxxxxxxxx>
---
 net/ipv4/tcp_ipv4.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 457f5b5d5d4a..ed03b8c48443 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1207,9 +1207,14 @@ int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
 	key->prefixlen = prefixlen;
 	key->l3index = l3index;
 	key->flags = flags;
+#if IS_ENABLED(CONFIG_IPV6)
 	memcpy(&key->addr, addr,
 	       (family == AF_INET6) ? sizeof(struct in6_addr) :
 				      sizeof(struct in_addr));
+#else
+	memcpy(&key->addr, addr, sizeof(struct in_addr));
+#endif
+
 	hlist_add_head_rcu(&key->node, &md5sig->head);
 	return 0;
 }
-- 
2.27.0