From: Arnd Bergmann <arnd@arndb.de>
Date: Mon, 31 Jul 2017 08:50:05 +0200
Subject: infiniband: avoid overflow warning
Patch-mainline: v4.14-rc1
Git-commit: 5f8a4db715ca21c3195b5eea24e26574c0f5acfa
References: bsc#1046306 FATE#322942

A sockaddr_in structure on the stack getting passed into rdma_ip2gid
triggers this warning, since we memcpy into a larger sockaddr_in6
structure:

In function 'memcpy',
    inlined from 'rdma_ip2gid' at include/rdma/ib_addr.h:175:3,
    inlined from 'addr_event.isra.4.constprop' at drivers/infiniband/core/roce_gid_mgmt.c:693:2,
    inlined from 'inetaddr_event' at drivers/infiniband/core/roce_gid_mgmt.c:716:9:
include/linux/string.h:305:4: error: call to '__read_overflow2' declared with attribute error: detected read beyond size of object passed as 2nd parameter

The warning seems appropriate here, but the code is also clearly
correct, so we really just want to shut up this instance of the
output.

The best way I found so far is to avoid the memcpy() call and instead
replace it with a struct assignment.

Fixes: 6974f0c4555e ("include/linux/string.h: add the option of fortified string.h functions")
Cc: Daniel Micay <danielmicay@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Doug Ledford <dledford@redhat.com>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 include/rdma/ib_addr.h |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/include/rdma/ib_addr.h
+++ b/include/rdma/ib_addr.h
@@ -172,7 +172,8 @@ static inline int rdma_ip2gid(struct soc
 				       (struct in6_addr *)gid);
 		break;
 	case AF_INET6:
-		memcpy(gid->raw, &((struct sockaddr_in6 *)addr)->sin6_addr, 16);
+		*(struct in6_addr *)&gid->raw =
+			((struct sockaddr_in6 *)addr)->sin6_addr;
 		break;
 	default:
 		return -EINVAL;