sockets: avoid string truncation warnings when copying UNIX path

In file included from /usr/include/string.h:494, from include/qemu/osdep.h:101, from util/qemu-sockets.c:18: In function ‘strncpy’, inlined from ‘unix_connect_saddr.isra.0’ at util/qemu-sockets.c:925:5: /usr/include/bits/string_fortified.h:106:10: warning: ‘__builtin_strncpy’ specified bound 108 equals destination size [-Wstringop-truncation] 106 | return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest)); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ In function ‘strncpy’, inlined from ‘unix_listen_saddr.isra.0’ at util/qemu-sockets.c:880:5: /usr/include/bits/string_fortified.h:106:10: warning: ‘__builtin_strncpy’ specified bound 108 equals destination size [-Wstringop-truncation] 106 | return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest)); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ We are already validating the UNIX socket path length earlier in the functions. If we save this string length when we first check it, then we can simply use memcpy instead of strcpy later, avoiding the gcc truncation warnings. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Stefano Garzarella <sgarzare@redhat.com> Message-Id: <20190501145052.12579-1-berrange@redhat.com> Signed-off-by: Laurent Vivier <laurent@vivier.eu>
DrenfongWong · May 3, 2019 · 2d2023c · 2d2023c
1 parent 9176a58
commit 2d2023c
Showing 1 changed file with 8 additions and 4 deletions.
diff --git a/util/qemu-sockets.c b/util/qemu-sockets.c
@@ -830,6 +830,7 @@ static int unix_listen_saddr(UnixSocketAddress *saddr,
     int sock, fd;
     char *pathbuf = NULL;
     const char *path;
+    size_t pathlen;
 
     sock = qemu_socket(PF_UNIX, SOCK_STREAM, 0);
     if (sock < 0) {
@@ -845,7 +846,8 @@ static int unix_listen_saddr(UnixSocketAddress *saddr,
         path = pathbuf = g_strdup_printf("%s/qemu-socket-XXXXXX", tmpdir);
     }
 
-    if (strlen(path) > sizeof(un.sun_path)) {
+    pathlen = strlen(path);
+    if (pathlen > sizeof(un.sun_path)) {
         error_setg(errp, "UNIX socket path '%s' is too long", path);
         error_append_hint(errp, "Path must be less than %zu bytes\n",
                           sizeof(un.sun_path));
@@ -877,7 +879,7 @@ static int unix_listen_saddr(UnixSocketAddress *saddr,
 
     memset(&un, 0, sizeof(un));
     un.sun_family = AF_UNIX;
-    strncpy(un.sun_path, path, sizeof(un.sun_path));
+    memcpy(un.sun_path, path, pathlen);
 
     if (bind(sock, (struct sockaddr*) &un, sizeof(un)) < 0) {
         error_setg_errno(errp, errno, "Failed to bind socket to %s", path);
@@ -901,6 +903,7 @@ static int unix_connect_saddr(UnixSocketAddress *saddr, Error **errp)
 {
     struct sockaddr_un un;
     int sock, rc;
+    size_t pathlen;
 
     if (saddr->path == NULL) {
         error_setg(errp, "unix connect: no path specified");
@@ -913,7 +916,8 @@ static int unix_connect_saddr(UnixSocketAddress *saddr, Error **errp)
         return -1;
     }
 
-    if (strlen(saddr->path) > sizeof(un.sun_path)) {
+    pathlen = strlen(saddr->path);
+    if (pathlen > sizeof(un.sun_path)) {
         error_setg(errp, "UNIX socket path '%s' is too long", saddr->path);
         error_append_hint(errp, "Path must be less than %zu bytes\n",
                           sizeof(un.sun_path));
@@ -922,7 +926,7 @@ static int unix_connect_saddr(UnixSocketAddress *saddr, Error **errp)
 
     memset(&un, 0, sizeof(un));
     un.sun_family = AF_UNIX;
-    strncpy(un.sun_path, saddr->path, sizeof(un.sun_path));
+    memcpy(un.sun_path, saddr->path, pathlen);
 
     /* connect to peer */
     do {