bpo-38282: Rewrite getsockaddrarg() helper function (GH-16698)

Rewrite getsockaddrarg() helper function of socketmodule.c (_socket
module) to prevent a false alarm when compiling codde using GCC with
_FORTIFY_SOURCE=2. Pass a pointer of the sock_addr_t union, rather
than passing a pointer to a sockaddr structure.

Add "struct sockaddr_tipc tipc;" to the sock_addr_t union.

2 files changed, 25 insertions, 39 deletions

diff --git a/Modules/socketmodule.c b/Modules/socketmodule.c
index c649fa3c98..d42fa7ce18 100644
--- a/Modules/socketmodule.c
+++ b/Modules/socketmodule.c
@@ -1688,14 +1688,13 @@ idna_converter(PyObject *obj, struct maybe_idna *data)
 
 static int
 getsockaddrarg(PySocketSockObject *s, PyObject *args,
-               struct sockaddr *addr_ret, int *len_ret, const char *caller)
+               sock_addr_t *addrbuf, int *len_ret, const char *caller)
 {
     switch (s->sock_family) {
 
 #if defined(AF_UNIX)
     case AF_UNIX:
     {
-        struct sockaddr_un* addr;
         Py_buffer path;
         int retval = 0;
 
@@ -1713,7 +1712,7 @@ getsockaddrarg(PySocketSockObject *s, PyObject *args,
         }
         assert(path.len >= 0);
 
-        addr = (struct sockaddr_un*)addr_ret;
+        struct sockaddr_un* addr = &addrbuf->un;
 #ifdef __linux__
         if (path.len > 0 && *(const char *)path.buf == 0) {
             /* Linux abstract namespace extension */
@@ -1748,9 +1747,8 @@ getsockaddrarg(PySocketSockObject *s, PyObject *args,
 #if defined(AF_NETLINK)
     case AF_NETLINK:
     {
-        struct sockaddr_nl* addr;
         int pid, groups;
-        addr = (struct sockaddr_nl *)addr_ret;
+        struct sockaddr_nl* addr = &addrbuf->nl;
         if (!PyTuple_Check(args)) {
             PyErr_Format(
                 PyExc_TypeError,
@@ -1776,9 +1774,8 @@ getsockaddrarg(PySocketSockObject *s, PyObject *args,
 #if defined(AF_QIPCRTR)
     case AF_QIPCRTR:
     {
-        struct sockaddr_qrtr* addr;
         unsigned int node, port;
-        addr = (struct sockaddr_qrtr *)addr_ret;
+        struct sockaddr_qrtr* addr = &addrbuf->sq;
         if (!PyTuple_Check(args)) {
             PyErr_Format(
                 PyExc_TypeError,
@@ -1800,9 +1797,8 @@ getsockaddrarg(PySocketSockObject *s, PyObject *args,
 #if defined(AF_VSOCK)
     case AF_VSOCK:
     {
-        struct sockaddr_vm* addr;
+        struct sockaddr_vm* addr = &addrbuf->vm;
         int port, cid;
-        addr = (struct sockaddr_vm *)addr_ret;
         memset(addr, 0, sizeof(struct sockaddr_vm));
         if (!PyTuple_Check(args)) {
             PyErr_Format(
@@ -1830,7 +1826,6 @@ getsockaddrarg(PySocketSockObject *s, PyObject *args,
 
     case AF_INET:
     {
-        struct sockaddr_in* addr;
         struct maybe_idna host = {NULL, NULL};
         int port, result;
         if (!PyTuple_Check(args)) {
@@ -1852,7 +1847,7 @@ getsockaddrarg(PySocketSockObject *s, PyObject *args,
             }
             return 0;
         }
-        addr=(struct sockaddr_in*)addr_ret;
+        struct sockaddr_in* addr = &addrbuf->in;
         result = setipaddr(host.buf, (struct sockaddr *)addr,
                            sizeof(*addr),  AF_INET);
         idna_cleanup(&host);
@@ -1873,7 +1868,6 @@ getsockaddrarg(PySocketSockObject *s, PyObject *args,
 #ifdef ENABLE_IPV6
     case AF_INET6:
     {
-        struct sockaddr_in6* addr;
         struct maybe_idna host = {NULL, NULL};
         int port, result;
         unsigned int flowinfo, scope_id;
@@ -1898,7 +1892,7 @@ getsockaddrarg(PySocketSockObject *s, PyObject *args,
             }
             return 0;
         }
-        addr = (struct sockaddr_in6*)addr_ret;
+        struct sockaddr_in6* addr = &addrbuf->in6;
         result = setipaddr(host.buf, (struct sockaddr *)addr,
                            sizeof(*addr), AF_INET6);
         idna_cleanup(&host);
@@ -1932,10 +1926,9 @@ getsockaddrarg(PySocketSockObject *s, PyObject *args,
 #ifdef BTPROTO_L2CAP
         case BTPROTO_L2CAP:
         {
-            struct sockaddr_l2 *addr;
             const char *straddr;
 
-            addr = (struct sockaddr_l2 *)addr_ret;
+            struct sockaddr_l2 *addr = &addrbuf->bt_l2;
             memset(addr, 0, sizeof(struct sockaddr_l2));
             _BT_L2_MEMB(addr, family) = AF_BLUETOOTH;
             if (!PyArg_ParseTuple(args, "si", &straddr,
@@ -1953,10 +1946,8 @@ getsockaddrarg(PySocketSockObject *s, PyObject *args,
 #endif /* BTPROTO_L2CAP */
         case BTPROTO_RFCOMM:
         {
-            struct sockaddr_rc *addr;
             const char *straddr;
-
-            addr = (struct sockaddr_rc *)addr_ret;
+            struct sockaddr_rc *addr = &addrbuf->bt_rc;
             _BT_RC_MEMB(addr, family) = AF_BLUETOOTH;
             if (!PyArg_ParseTuple(args, "si", &straddr,
                                   &_BT_RC_MEMB(addr, channel))) {
@@ -1973,7 +1964,7 @@ getsockaddrarg(PySocketSockObject *s, PyObject *args,
 #ifdef BTPROTO_HCI
         case BTPROTO_HCI:
         {
-            struct sockaddr_hci *addr = (struct sockaddr_hci *)addr_ret;
+            struct sockaddr_hci *addr = &addrbuf->bt_hci;
 #if defined(__NetBSD__) || defined(__DragonFly__)
             const char *straddr;
             _BT_HCI_MEMB(addr, family) = AF_BLUETOOTH;
@@ -1999,10 +1990,9 @@ getsockaddrarg(PySocketSockObject *s, PyObject *args,
 #if !defined(__FreeBSD__)
         case BTPROTO_SCO:
         {
-            struct sockaddr_sco *addr;
             const char *straddr;
 
-            addr = (struct sockaddr_sco *)addr_ret;
+            struct sockaddr_sco *addr = &addrbuf->bt_sco;
             _BT_SCO_MEMB(addr, family) = AF_BLUETOOTH;
             if (!PyBytes_Check(args)) {
                 PyErr_Format(PyExc_OSError,
@@ -2029,7 +2019,6 @@ getsockaddrarg(PySocketSockObject *s, PyObject *args,
 #if defined(HAVE_NETPACKET_PACKET_H) && defined(SIOCGIFINDEX)
     case AF_PACKET:
     {
-        struct sockaddr_ll* addr;
         struct ifreq ifr;
         const char *interfaceName;
         int protoNumber;
@@ -2080,7 +2069,7 @@ getsockaddrarg(PySocketSockObject *s, PyObject *args,
             PyBuffer_Release(&haddr);
             return 0;
         }
-        addr = (struct sockaddr_ll*)addr_ret;
+        struct sockaddr_ll* addr = &addrbuf->ll;
         addr->sll_family = AF_PACKET;
         addr->sll_protocol = htons((short)protoNumber);
         addr->sll_ifindex = ifr.ifr_ifindex;
@@ -2103,7 +2092,6 @@ getsockaddrarg(PySocketSockObject *s, PyObject *args,
     {
         unsigned int atype, v1, v2, v3;
         unsigned int scope = TIPC_CLUSTER_SCOPE;
-        struct sockaddr_tipc *addr;
 
         if (!PyTuple_Check(args)) {
             PyErr_Format(
@@ -2121,7 +2109,7 @@ getsockaddrarg(PySocketSockObject *s, PyObject *args,
             return 0;
         }
 
-        addr = (struct sockaddr_tipc *) addr_ret;
+        struct sockaddr_tipc *addr = &addrbuf->tipc;
         memset(addr, 0, sizeof(struct sockaddr_tipc));
 
         addr->family = AF_TIPC;
@@ -2162,11 +2150,10 @@ getsockaddrarg(PySocketSockObject *s, PyObject *args,
 #endif
 #if defined(CAN_RAW) || defined(CAN_BCM)
         {
-            struct sockaddr_can *addr;
             PyObject *interfaceName;
             struct ifreq ifr;
             Py_ssize_t len;
-            addr = (struct sockaddr_can *)addr_ret;
+            struct sockaddr_can *addr = &addrbuf->can;
 
             if (!PyTuple_Check(args)) {
                 PyErr_Format(PyExc_TypeError,
@@ -2213,13 +2200,12 @@ getsockaddrarg(PySocketSockObject *s, PyObject *args,
 #ifdef CAN_ISOTP
         case CAN_ISOTP:
         {
-            struct sockaddr_can *addr;
             PyObject *interfaceName;
             struct ifreq ifr;
             Py_ssize_t len;
             unsigned long int rx_id, tx_id;
 
-            addr = (struct sockaddr_can *)addr_ret;
+            struct sockaddr_can *addr = &addrbuf->can;
 
             if (!PyArg_ParseTuple(args, "O&kk", PyUnicode_FSConverter,
                                               &interfaceName,
@@ -2269,9 +2255,7 @@ getsockaddrarg(PySocketSockObject *s, PyObject *args,
 #ifdef SYSPROTO_CONTROL
         case SYSPROTO_CONTROL:
         {
-            struct sockaddr_ctl *addr;
-
-            addr = (struct sockaddr_ctl *)addr_ret;
+            struct sockaddr_ctl *addr = &addrbuf->ctl;
             addr->sc_family = AF_SYSTEM;
             addr->ss_sysaddr = AF_SYS_CONTROL;
 
@@ -2323,10 +2307,9 @@ getsockaddrarg(PySocketSockObject *s, PyObject *args,
 #ifdef HAVE_SOCKADDR_ALG
     case AF_ALG:
     {
-        struct sockaddr_alg *sa;
         const char *type;
         const char *name;
-        sa = (struct sockaddr_alg *)addr_ret;
+        struct sockaddr_alg *sa = &addrbuf->alg;
 
         memset(sa, 0, sizeof(*sa));
         sa->salg_family = AF_ALG;
@@ -3110,7 +3093,7 @@ sock_bind(PySocketSockObject *s, PyObject *addro)
     int addrlen;
     int res;
 
-    if (!getsockaddrarg(s, addro, SAS2SA(&addrbuf), &addrlen, "bind")) {
+    if (!getsockaddrarg(s, addro, &addrbuf, &addrlen, "bind")) {
         return NULL;
     }
 
@@ -3280,7 +3263,7 @@ sock_connect(PySocketSockObject *s, PyObject *addro)
     int addrlen;
     int res;
 
-    if (!getsockaddrarg(s, addro, SAS2SA(&addrbuf), &addrlen, "connect")) {
+    if (!getsockaddrarg(s, addro, &addrbuf, &addrlen, "connect")) {
         return NULL;
     }
 
@@ -3311,7 +3294,7 @@ sock_connect_ex(PySocketSockObject *s, PyObject *addro)
     int addrlen;
     int res;
 
-    if (!getsockaddrarg(s, addro, SAS2SA(&addrbuf), &addrlen, "connect_ex")) {
+    if (!getsockaddrarg(s, addro, &addrbuf, &addrlen, "connect_ex")) {
         return NULL;
     }
 
@@ -4316,7 +4299,7 @@ sock_sendto(PySocketSockObject *s, PyObject *args)
         return select_error();
     }
 
-    if (!getsockaddrarg(s, addro, SAS2SA(&addrbuf), &addrlen, "sendto")) {
+    if (!getsockaddrarg(s, addro, &addrbuf, &addrlen, "sendto")) {
         PyBuffer_Release(&pbuf);
         return NULL;
     }
@@ -4451,7 +4434,7 @@ sock_sendmsg(PySocketSockObject *s, PyObject *args)
 
     /* Parse destination address. */
     if (addr_arg != NULL && addr_arg != Py_None) {
-        if (!getsockaddrarg(s, addr_arg, SAS2SA(&addrbuf), &addrlen,
+        if (!getsockaddrarg(s, addr_arg, &addrbuf, &addrlen,
                             "sendmsg"))
         {
             goto finally;
diff --git a/Modules/socketmodule.h b/Modules/socketmodule.h
index 3d95fe709a..e06e4c3888 100644
--- a/Modules/socketmodule.h
+++ b/Modules/socketmodule.h
@@ -261,6 +261,9 @@ typedef union sock_addr {
 #ifdef AF_VSOCK
     struct sockaddr_vm vm;
 #endif
+#ifdef HAVE_LINUX_TIPC_H
+    struct sockaddr_tipc tipc;
+#endif
 } sock_addr_t;
 
 /* The object holding a socket.  It holds some extra information,