RDMA: Directly cast the sockaddr union to sockaddr

BugLink: https://bugs.launchpad.net/bugs/1845038

commit 641114d2 upstream.

gcc 9 now does allocation size tracking and thinks that passing the member
of a union and then accessing beyond that member's bounds is an overflow.

Instead of using the union member, use the entire union with a cast to
get to the sockaddr. gcc will now know that the memory extends the full
size of the union.
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Connor Kuehl <connor.kuehl@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

drivers/infiniband/core/addr.c

@@ -481,14 +481,13 @@ int rdma_addr_find_dmac_by_grh(const union ib_gid *sgid, const union ib_gid *dgi
 	struct net_device *dev;
 
 	union {
-		struct sockaddr     _sockaddr;
 		struct sockaddr_in  _sockaddr_in;
 		struct sockaddr_in6 _sockaddr_in6;
 	} sgid_addr, dgid_addr;
 
 
-	rdma_gid2ip(&sgid_addr._sockaddr, sgid);
-	rdma_gid2ip(&dgid_addr._sockaddr, dgid);
+	rdma_gid2ip((struct sockaddr *)&sgid_addr, sgid);
+	rdma_gid2ip((struct sockaddr *)&dgid_addr, dgid);
 
 	memset(&dev_addr, 0, sizeof(dev_addr));
 	dev_addr.bound_dev_if = if_index;
@@ -496,8 +495,9 @@ int rdma_addr_find_dmac_by_grh(const union ib_gid *sgid, const union ib_gid *dgi
 
 	ctx.addr = &dev_addr;
 	init_completion(&ctx.comp);
-	ret = rdma_resolve_ip(&self, &sgid_addr._sockaddr, &dgid_addr._sockaddr,
-			&dev_addr, 1000, resolve_cb, &ctx);
+	ret = rdma_resolve_ip(&self, (struct sockaddr *)&sgid_addr,
+			      (struct sockaddr *)&dgid_addr, &dev_addr, 1000,
+			      resolve_cb, &ctx);
 	if (ret)
 		return ret;
 
@@ -519,16 +519,15 @@ int rdma_addr_find_smac_by_sgid(union ib_gid *sgid, u8 *smac, u16 *vlan_id)
 	int ret = 0;
 	struct rdma_dev_addr dev_addr;
 	union {
-		struct sockaddr     _sockaddr;
 		struct sockaddr_in  _sockaddr_in;
 		struct sockaddr_in6 _sockaddr_in6;
 	} gid_addr;
 
-	rdma_gid2ip(&gid_addr._sockaddr, sgid);
+	rdma_gid2ip((struct sockaddr *)&gid_addr, sgid);
 
 	memset(&dev_addr, 0, sizeof(dev_addr));
 	dev_addr.net = &init_net;
-	ret = rdma_translate_ip(&gid_addr._sockaddr, &dev_addr, vlan_id);
+	ret = rdma_translate_ip((struct sockaddr *)&gid_addr, &dev_addr, vlan_id);
 	if (ret)
 		return ret;