Merge branch 'net-fix-error-warning-by-fstrict-flex-arrays-3'

Kuniyuki Iwashima says:

====================
net: Fix error/warning by -fstrict-flex-arrays=3.

df8fc4e ("kbuild: Enable -fstrict-flex-arrays=3") started applying
strict rules for standard string functions (strlen(), memcpy(), etc.) if
CONFIG_FORTIFY_SOURCE=y.

This series fixes two false positives caught by syzkaller.

v2: https://lore.kernel.org/netdev/20230720004410.87588-1-kuniyu@amazon.com/
v1: https://lore.kernel.org/netdev/20230719185322.44255-1-kuniyu@amazon.com/
====================

Link: https://lore.kernel.org/r/20230724213425.22920-1-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: kuba-moo

include/uapi/linux/if_packet.h

@@ -18,7 +18,11 @@ struct sockaddr_ll {
 	unsigned short	sll_hatype;
 	unsigned char	sll_pkttype;
 	unsigned char	sll_halen;
-	unsigned char	sll_addr[8];
+	union {
+		unsigned char	sll_addr[8];
+		/* Actual length is in sll_halen. */
+		__DECLARE_FLEX_ARRAY(unsigned char, sll_addr_flex);
+	};
 };
 
 /* Packet types */

net/packet/af_packet.c

@@ -3601,7 +3601,7 @@ static int packet_getname(struct socket *sock, struct sockaddr *uaddr,
 	if (dev) {
 		sll->sll_hatype = dev->type;
 		sll->sll_halen = dev->addr_len;
-		memcpy(sll->sll_addr, dev->dev_addr, dev->addr_len);
+		memcpy(sll->sll_addr_flex, dev->dev_addr, dev->addr_len);
 	} else {
 		sll->sll_hatype = 0;	/* Bad: we have no ARPHRD_UNSPEC */
 		sll->sll_halen = 0;

net/unix/af_unix.c

@@ -1208,10 +1208,8 @@ static int unix_bind_bsd(struct sock *sk, struct sockaddr_un *sunaddr,
 	struct path parent;
 	int err;
 
-	unix_mkname_bsd(sunaddr, addr_len);
-	addr_len = strlen(sunaddr->sun_path) +
-		offsetof(struct sockaddr_un, sun_path) + 1;
-
+	addr_len = strnlen(sunaddr->sun_path, sizeof(sunaddr->sun_path))
+		+ offsetof(struct sockaddr_un, sun_path) + 1;
 	addr = unix_create_addr(sunaddr, addr_len);
 	if (!addr)
 		return -ENOMEM;