netdev - [PATCH 4/5][next] uapi: net: arp: Avoid -Wflex-array-member-not-at-end warnings

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Message-ID: <f04e61e1c69991559f5589080462320bf772499d.1729037131.git.gustavoars@kernel.org>
Date: Tue, 15 Oct 2024 18:32:43 -0600
From: "Gustavo A. R. Silva" <gustavoars@...nel.org>
To: Andrew Lunn <andrew+netdev@...n.ch>, David Ahern <dsahern@...nel.org>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	"Gustavo A. R. Silva" <gustavoars@...nel.org>,
	linux-hardening@...r.kernel.org, Kees Cook <kees@...nel.org>
Subject: [PATCH 4/5][next] uapi: net: arp: Avoid
 -Wflex-array-member-not-at-end warnings

-Wflex-array-member-not-at-end was introduced in GCC-14, and we are
getting ready to enable it, globally.

Address the following warnings by changing the type of the middle struct
members in a couple of composite structs, which are currently causing
trouble, from `struct sockaddr` to `struct sockaddr_legacy`. Note that
the latter struct doesn't contain a flexible-array member.

include/uapi/linux/if_arp.h:118:25: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
include/uapi/linux/if_arp.h:119:25: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
include/uapi/linux/if_arp.h:121:25: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
include/uapi/linux/if_arp.h:126:25: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
include/uapi/linux/if_arp.h:127:25: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]

Also, update some related code, accordingly.

No binary differences are present after these changes.

Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>
---
 include/uapi/linux/if_arp.h | 18 +++++++++---------
 net/ipv4/arp.c              |  2 +-
 2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/include/uapi/linux/if_arp.h b/include/uapi/linux/if_arp.h
index 4783af9fe520..cb6813f7783a 100644
--- a/include/uapi/linux/if_arp.h
+++ b/include/uapi/linux/if_arp.h
@@ -115,18 +115,18 @@
 
 /* ARP ioctl request. */
 struct arpreq {
-	struct sockaddr	arp_pa;		/* protocol address		 */
-	struct sockaddr	arp_ha;		/* hardware address		 */
-	int		arp_flags;	/* flags			 */
-	struct sockaddr arp_netmask;    /* netmask (only for proxy arps) */
-	char		arp_dev[IFNAMSIZ];
+	struct sockaddr_legacy	arp_pa;		/* protocol address		 */
+	struct sockaddr_legacy	arp_ha;		/* hardware address		 */
+	int			arp_flags;	/* flags			 */
+	struct sockaddr_legacy	arp_netmask;    /* netmask (only for proxy arps) */
+	char			arp_dev[IFNAMSIZ];
 };
 
 struct arpreq_old {
-	struct sockaddr	arp_pa;		/* protocol address		 */
-	struct sockaddr	arp_ha;		/* hardware address		 */
-	int		arp_flags;	/* flags			 */
-	struct sockaddr	arp_netmask;    /* netmask (only for proxy arps) */
+	struct sockaddr_legacy	arp_pa;		/* protocol address		 */
+	struct sockaddr_legacy	arp_ha;		/* hardware address		 */
+	int			arp_flags;	/* flags			 */
+	struct sockaddr		arp_netmask;    /* netmask (only for proxy arps) */
 };
 
 /* ARP Flag values. */
diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
index 11c1519b3699..3a97efe1587b 100644
--- a/net/ipv4/arp.c
+++ b/net/ipv4/arp.c
@@ -1185,7 +1185,7 @@ static int arp_req_get(struct net *net, struct arpreq *r)
 
 	read_lock_bh(&neigh->lock);
 	memcpy(r->arp_ha.sa_data, neigh->ha,
-	       min(dev->addr_len, sizeof(r->arp_ha.sa_data_min)));
+	       min(dev->addr_len, sizeof(r->arp_ha.sa_data)));
 	r->arp_flags = arp_state_to_flags(neigh);
 	read_unlock_bh(&neigh->lock);
 
-- 
2.34.1