Commit 2d2023c3 authored by Daniel P. Berrangé's avatar Daniel P. Berrangé Committed by Laurent Vivier
Browse files

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: default avatarDaniel P. Berrangé <berrange@redhat.com>
Reviewed-by: default avatarEric Blake <eblake@redhat.com>
Reviewed-by: default avatarStefano Garzarella <sgarzare@redhat.com>
Message-Id: <20190501145052.12579-1-berrange@redhat.com>
Signed-off-by: default avatarLaurent Vivier <laurent@vivier.eu>
parent 9176a580

util/qemu-sockets.c

+8 −4
Original line number Diff line number Diff line
@@ -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 {