net: Convert struct sockaddr to fixed-size "sa_data[14]"

Revert struct sockaddr from flexible array to fixed 14-byte "sa_data",
to solve over 36,000 -Wflex-array-member-not-at-end warnings, since
struct sockaddr is embedded within many network structs.

With socket/proto sockaddr-based internal APIs switched to use struct
sockaddr_unsized, there should be no more uses of struct sockaddr that
depend on reading beyond the end of struct sockaddr::sa_data that might
trigger bounds checking.

Comparing an x86_64 "allyesconfig" vmlinux build before and after this
patch showed no new "ud1" instructions from CONFIG_UBSAN_BOUNDS nor any
new "field-spanning" memcpy CONFIG_FORTIFY_SOURCE instrumentations.

Cc: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Kees Cook <kees@kernel.org>
Link: https://patch.msgid.link/20251104002617.2752303-8-kees@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/linux/socket.h b/include/linux/socket.h
index 7b1a01be29da8cfddac7d110d91fc3121ca78f94..944027f9765e713dc048cd46315c85468b1dfe6d 100644 (file)
--- a/include/linux/socket.h
+++ b/include/linux/socket.h
@@ -32,12 +32,10 @@ typedef __kernel_sa_family_t        sa_family_t;
  *     1003.1g requires sa_family_t and that sa_data is char.
  */
 
+/* Deprecated for in-kernel use. Use struct sockaddr_unsized instead. */
 struct sockaddr {
        sa_family_t     sa_family;      /* address family, AF_xxx       */
-       union {
-               char sa_data_min[14];           /* Minimum 14 bytes of protocol address */
-               DECLARE_FLEX_ARRAY(char, sa_data);
-       };
+       char            sa_data[14];    /* 14 bytes of protocol address */
 };
 
 /**

diff --git a/net/core/dev.c b/net/core/dev.c
index ba39146bbd25f7a5920e3de58df4915853e196de..537aa43edff0e4bfedb42593146cfdf7511d8c37 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -9973,7 +9973,7 @@ DECLARE_RWSEM(dev_addr_sem);
 /* "sa" is a true struct sockaddr with limited "sa_data" member. */
 int netif_get_mac_address(struct sockaddr *sa, struct net *net, char *dev_name)
 {
-       size_t size = sizeof(sa->sa_data_min);
+       size_t size = sizeof(sa->sa_data);
        struct net_device *dev;
        int ret = 0;
 

diff --git a/net/core/dev_ioctl.c b/net/core/dev_ioctl.c
index ad54b12d4b4c80bccc526278370319dfc36fb703..b3ce0fb24a69b1cbd255b8268ca209a5bcb864be 100644 (file)
--- a/net/core/dev_ioctl.c
+++ b/net/core/dev_ioctl.c
@@ -596,7 +596,7 @@ static int dev_ifsioc(struct net *net, struct ifreq *ifr, void __user *data,
                if (ifr->ifr_hwaddr.sa_family != dev->type)
                        return -EINVAL;
                memcpy(dev->broadcast, ifr->ifr_hwaddr.sa_data,
-                      min(sizeof(ifr->ifr_hwaddr.sa_data_min),
+                      min(sizeof(ifr->ifr_hwaddr.sa_data),
                           (size_t)dev->addr_len));
                netdev_lock_ops(dev);
                call_netdevice_notifiers(NETDEV_CHANGEADDR, dev);

diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
index f3bfecf8a2341c5e6583bd711e8b59cd59bdf872..7f3863daaa407624359e8309cf9d661e1cdb03ac 100644 (file)
--- a/net/ipv4/arp.c
+++ b/net/ipv4/arp.c
@@ -1189,7 +1189,7 @@ 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);
 

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index fccad2a529cc18bcfa56e8eba4bcee524602e05f..494d628d10a5105a6a32788b4673993f218ec881 100644 (file)
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -3284,7 +3284,7 @@ static int packet_bind_spkt(struct socket *sock, struct sockaddr_unsized *uaddr,
 {
        struct sock *sk = sock->sk;
        struct sockaddr *sa = (struct sockaddr *)uaddr;
-       char name[sizeof(sa->sa_data_min) + 1];
+       char name[sizeof(sa->sa_data) + 1];
 
        /*
         *      Check legality
@@ -3295,8 +3295,8 @@ static int packet_bind_spkt(struct socket *sock, struct sockaddr_unsized *uaddr,
        /* uaddr->sa_data comes from the userspace, it's not guaranteed to be
         * zero-terminated.
         */
-       memcpy(name, sa->sa_data, sizeof(sa->sa_data_min));
-       name[sizeof(sa->sa_data_min)] = 0;
+       memcpy(name, sa->sa_data, sizeof(sa->sa_data));
+       name[sizeof(sa->sa_data)] = 0;
 
        return packet_do_bind(sk, name, 0, 0);
 }
@@ -3581,11 +3581,11 @@ static int packet_getname_spkt(struct socket *sock, struct sockaddr *uaddr,
                return -EOPNOTSUPP;
 
        uaddr->sa_family = AF_PACKET;
-       memset(uaddr->sa_data, 0, sizeof(uaddr->sa_data_min));
+       memset(uaddr->sa_data, 0, sizeof(uaddr->sa_data));
        rcu_read_lock();
        dev = dev_get_by_index_rcu(sock_net(sk), READ_ONCE(pkt_sk(sk)->ifindex));
        if (dev)
-               strscpy(uaddr->sa_data, dev->name, sizeof(uaddr->sa_data_min));
+               strscpy(uaddr->sa_data, dev->name, sizeof(uaddr->sa_data));
        rcu_read_unlock();
 
        return sizeof(*uaddr);

diff --git a/tools/perf/trace/beauty/include/linux/socket.h b/tools/perf/trace/beauty/include/linux/socket.h
index 3b262487ec06032b885cad017ec828cc6a4142db..77d7c59f5d8b1cb2466ac7890147ca81ac7289df 100644 (file)
--- a/tools/perf/trace/beauty/include/linux/socket.h
+++ b/tools/perf/trace/beauty/include/linux/socket.h
@@ -34,10 +34,7 @@ typedef __kernel_sa_family_t sa_family_t;
 
 struct sockaddr {
        sa_family_t     sa_family;      /* address family, AF_xxx       */
-       union {
-               char sa_data_min[14];           /* Minimum 14 bytes of protocol address */
-               DECLARE_FLEX_ARRAY(char, sa_data);
-       };
+       char            sa_data[14];    /* 14 bytes of protocol address */
 };
 
 struct linger {