-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 __kernel_sockaddr_legacy` in 
UAPI, and `struct sockaddr_legacy` for the rest of the kernel code.

include/uapi/linux/route.h:33:25: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
include/uapi/linux/route.h:34:25: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
include/uapi/linux/route.h:35:25: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end
include/net/compat.h:34:25: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
include/net/compat.h:35:25: 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.

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
 include/net/compat.h       | 30 +++++++++++++++---------------
 include/uapi/linux/route.h | 28 ++++++++++++++--------------
 net/appletalk/ddp.c        |  2 +-
 net/ipv4/af_inet.c         |  2 +-
 net/ipv4/fib_frontend.c    |  2 +-
 5 files changed, 32 insertions(+), 32 deletions(-)

diff --git a/include/net/compat.h b/include/net/compat.h
index 84c163f40f38..89e891d8dcf3 100644
--- a/include/net/compat.h
+++ b/include/net/compat.h
@@ -29,21 +29,21 @@ struct compat_cmsghdr {
 };
 
 struct compat_rtentry {
-	u32		rt_pad1;
-	struct sockaddr rt_dst;         /* target address               */
-	struct sockaddr rt_gateway;     /* gateway addr (RTF_GATEWAY)   */
-	struct sockaddr rt_genmask;     /* target network mask (IP)     */
-	unsigned short	rt_flags;
-	short		rt_pad2;
-	u32		rt_pad3;
-	unsigned char	rt_tos;
-	unsigned char	rt_class;
-	short		rt_pad4;
-	short		rt_metric;      /* +1 for binary compatibility! */
-	compat_uptr_t	rt_dev;         /* forcing the device at add    */
-	u32		rt_mtu;         /* per route MTU/Window         */
-	u32		rt_window;      /* Window clamping              */
-	unsigned short  rt_irtt;        /* Initial RTT                  */
+	u32			rt_pad1;
+	struct sockaddr_legacy	rt_dst;         /* target address               */
+	struct sockaddr_legacy	rt_gateway;     /* gateway addr (RTF_GATEWAY)   */
+	struct sockaddr_legacy	rt_genmask;     /* target network mask (IP)     */
+	unsigned short		rt_flags;
+	short			rt_pad2;
+	u32			rt_pad3;
+	unsigned char		rt_tos;
+	unsigned char		rt_class;
+	short			rt_pad4;
+	short			rt_metric;      /* +1 for binary compatibility! */
+	compat_uptr_t		rt_dev;         /* forcing the device at add    */
+	u32			rt_mtu;         /* per route MTU/Window         */
+	u32			rt_window;      /* Window clamping              */
+	unsigned short		rt_irtt;        /* Initial RTT                  */
 };
 
 int __get_compat_msghdr(struct msghdr *kmsg, struct compat_msghdr *msg,
diff --git a/include/uapi/linux/route.h b/include/uapi/linux/route.h
index a0de9a7331a2..43fd79f90a47 100644
--- a/include/uapi/linux/route.h
+++ b/include/uapi/linux/route.h
@@ -29,22 +29,22 @@
 
 /* This structure gets passed by the SIOCADDRT and SIOCDELRT calls. */
 struct rtentry {
-	unsigned long	rt_pad1;
-	struct sockaddr	rt_dst;		/* target address		*/
-	struct sockaddr	rt_gateway;	/* gateway addr (RTF_GATEWAY)	*/
-	struct sockaddr	rt_genmask;	/* target network mask (IP)	*/
-	unsigned short	rt_flags;
-	short		rt_pad2;
-	unsigned long	rt_pad3;
-	void		*rt_pad4;
-	short		rt_metric;	/* +1 for binary compatibility!	*/
-	char __user	*rt_dev;	/* forcing the device at add	*/
-	unsigned long	rt_mtu;		/* per route MTU/Window 	*/
+	unsigned long			rt_pad1;
+	struct __kernel_sockaddr_legacy	rt_dst;		/* target address		*/
+	struct __kernel_sockaddr_legacy	rt_gateway;	/* gateway addr (RTF_GATEWAY)	*/
+	struct __kernel_sockaddr_legacy	rt_genmask;	/* target network mask (IP)	*/
+	unsigned short			rt_flags;
+	short				rt_pad2;
+	unsigned long			rt_pad3;
+	void				*rt_pad4;
+	short				rt_metric;	/* +1 for binary compatibility!	*/
+	char __user			*rt_dev;	/* forcing the device at add	*/
+	unsigned long			rt_mtu;		/* per route MTU/Window		*/
 #ifndef __KERNEL__
-#define rt_mss	rt_mtu			/* Compatibility :-(            */
+#define rt_mss	rt_mtu					/* Compatibility :-(            */
 #endif
-	unsigned long	rt_window;	/* Window clamping 		*/
-	unsigned short	rt_irtt;	/* Initial RTT			*/
+	unsigned long			rt_window;	/* Window clamping		*/
+	unsigned short			rt_irtt;	/* Initial RTT			*/
 };
 
 
diff --git a/net/appletalk/ddp.c b/net/appletalk/ddp.c
index b068651984fe..aac82a4af36f 100644
--- a/net/appletalk/ddp.c
+++ b/net/appletalk/ddp.c
@@ -1832,7 +1832,7 @@ static int atalk_compat_routing_ioctl(struct sock *sk, unsigned int cmd,
 	struct rtentry rt;
 
 	if (copy_from_user(&rt.rt_dst, &ur->rt_dst,
-			3 * sizeof(struct sockaddr)) ||
+			3 * sizeof(struct sockaddr_legacy)) ||
 	    get_user(rt.rt_flags, &ur->rt_flags) ||
 	    get_user(rt.rt_metric, &ur->rt_metric) ||
 	    get_user(rt.rt_mtu, &ur->rt_mtu) ||
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 8095e82de808..3beb52261b4b 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -1019,7 +1019,7 @@ static int inet_compat_routing_ioctl(struct sock *sk, unsigned int cmd,
 	struct rtentry rt;
 
 	if (copy_from_user(&rt.rt_dst, &ur->rt_dst,
-			3 * sizeof(struct sockaddr)) ||
+			3 * sizeof(struct sockaddr_legacy)) ||
 	    get_user(rt.rt_flags, &ur->rt_flags) ||
 	    get_user(rt.rt_metric, &ur->rt_metric) ||
 	    get_user(rt.rt_mtu, &ur->rt_mtu) ||
diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index 53bd26315df5..88c7a79946f2 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -452,7 +452,7 @@ int fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst,
 				     itag);
 }
 
-static inline __be32 sk_extract_addr(struct sockaddr *addr)
+static inline __be32 sk_extract_addr(struct sockaddr_legacy *addr)
 {
 	return ((struct sockaddr_in *) addr)->sin_addr.s_addr;
 }
-- 
2.34.1

On Thu, Oct 24, 2024 at 03:14:31PM -0600, Gustavo A. R. Silva wrote:
> -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 __kernel_sockaddr_legacy` in 
> UAPI, and `struct sockaddr_legacy` for the rest of the kernel code.
> 
> include/uapi/linux/route.h:33:25: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
> include/uapi/linux/route.h:34:25: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
> include/uapi/linux/route.h:35:25: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end
> include/net/compat.h:34:25: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
> include/net/compat.h:35:25: 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.
> 
> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Looks right, including the helper prototype update.

Reviewed-by: Kees Cook <kees@kernel.org>

-- 
Kees Cook