RDMA/core: Fix broadcast address falsely detected as local

commit 942cd47 upstream.

When rdma_resolve_addr() is invoked with a broadcast destination on an
IPoIB interface, is_dst_local() inspects the resolved route and
incorrectly concludes that the address is local. As a result, the
resolution fails with -ENODEV.
The issue stems from using '&' to compare rt_type with RTN_LOCAL. The
RTN_* values form a sequential enum, not a bitmask (RTN_LOCAL=2,
RTN_BROADCAST=3). Thus, "rt_type & RTN_LOCAL" yields a non-zero result
for a broadcast route as well.

Replace '&' with '==' when comparing rt_type against RTN_LOCAL.

Link: https://patch.msgid.link/r/20260609-fix-rdma-resolve-addr-v1-1-449b8b4e6c09@nvidia.com
Cc: stable@vger.kernel.org
Fixes: c31e403 ("RDMA/core: Use route entry flag to decide on loopback traffic")
Signed-off-by: Maher Sanalla <msanalla@nvidia.com>
Reviewed-by: Vlad Dumitrescu <vdumitrescu@nvidia.com>
Signed-off-by: Edward Srouji <edwards@nvidia.com>
Reviewed-by: Parav Pandit <parav@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: msanalla

drivers/infiniband/core/addr.c

@@ -439,7 +439,7 @@ static int addr6_resolve(struct sockaddr *src_sock,
 static bool is_dst_local(const struct dst_entry *dst)
 {
 	if (dst->ops->family == AF_INET)
-		return !!(dst_rtable(dst)->rt_type & RTN_LOCAL);
+		return dst_rtable(dst)->rt_type == RTN_LOCAL;
 	else if (dst->ops->family == AF_INET6)
 		return !!(dst_rt6_info(dst)->rt6i_flags & RTF_LOCAL);
 	else