libxl: make libxl__wait_for_device_model use libxl__spawn_starrting directly

Instead of indirecting via libxl_device_model_starting. This fixes a
segmentation fault using stubdomains where starting->for_spawn is
(validly) NULL because starting a stubdom doesn't need to spawn a
process.

Most callers of libxl__wait_for_device_model already pass NULL for
this variable (because they are not on the starting path) so on
libxl__confirm_device_model_startup needs to change.

Reported-by: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>

diff --git a/tools/libxl/libxl_device.c b/tools/libxl/libxl_device.c
index 1b9e984e391394c6d58471b0fb0c4fab3e38212a..7931b11abcf4abad9112fd8a3be969896f1e09e0 100644 (file)
--- a/tools/libxl/libxl_device.c
+++ b/tools/libxl/libxl_device.c
@@ -522,7 +522,7 @@ out:
 
 int libxl__wait_for_device_model(libxl__gc *gc,
                                  uint32_t domid, char *state,
-                                 libxl__device_model_starting *starting,
+                                 libxl__spawn_starting *spawning,
                                  int (*check_callback)(libxl__gc *gc,
                                                        uint32_t domid,
                                                        const char *state,
@@ -552,12 +552,12 @@ int libxl__wait_for_device_model(libxl__gc *gc,
     tv.tv_sec = LIBXL_DEVICE_MODEL_START_TIMEOUT;
     tv.tv_usec = 0;
     nfds = xs_fileno(xsh) + 1;
-    if (starting && starting->for_spawn->fd > xs_fileno(xsh))
-        nfds = starting->for_spawn->fd + 1;
+    if (spawning && spawning->fd > xs_fileno(xsh))
+        nfds = spawning->fd + 1;
 
     while (rc > 0 || (!rc && tv.tv_sec > 0)) {
-        if ( starting ) {
-            rc = libxl__spawn_check(gc, starting->for_spawn);
+        if ( spawning ) {
+            rc = libxl__spawn_check(gc, spawning);
             if ( rc ) {
                 LIBXL__LOG(ctx, LIBXL__LOG_ERROR,
                            "Device Model died during startup");
@@ -586,8 +586,8 @@ again:
         free(p);
         FD_ZERO(&rfds);
         FD_SET(xs_fileno(xsh), &rfds);
-        if (starting)
-            FD_SET(starting->for_spawn->fd, &rfds);
+        if (spawning)
+            FD_SET(spawning->fd, &rfds);
         rc = select(nfds, &rfds, NULL, NULL, &tv);
         if (rc > 0) {
             if (FD_ISSET(xs_fileno(xsh), &rfds)) {
@@ -597,9 +597,9 @@ again:
                 else
                     goto again;
             }
-            if (starting && FD_ISSET(starting->for_spawn->fd, &rfds)) {
+            if (spawning && FD_ISSET(spawning->fd, &rfds)) {
                 unsigned char dummy;
-                if (read(starting->for_spawn->fd, &dummy, sizeof(dummy)) != 1)
+                if (read(spawning->fd, &dummy, sizeof(dummy)) != 1)
                     LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_DEBUG,
                                      "failed to read spawn status pipe");
             }

diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
index e854a50462d78d9c9a5b69da4a57733cc56da549..254f016889fec08d7705654c773e37801874c21b 100644 (file)
--- a/tools/libxl/libxl_dm.c
+++ b/tools/libxl/libxl_dm.c
@@ -920,7 +920,7 @@ int libxl__confirm_device_model_startup(libxl__gc *gc,
 {
     int detach;
     int problem = libxl__wait_for_device_model(gc, starting->domid, "running",
-                                               starting, NULL, NULL);
+                                               starting->for_spawn, NULL, NULL);
     detach = detach_device_model(gc, starting);
     return problem ? problem : detach;
 }

diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index b73b6c46cd393393ac9de5e11f3463b22c43281f..0e1aac8fa0da740625b7c9472bb4ef2f68f958d6 100644 (file)
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -283,7 +283,7 @@ _hidden int libxl__confirm_device_model_startup(libxl__gc *gc,
 _hidden int libxl__detach_device_model(libxl__gc *gc, libxl__device_model_starting *starting);
 _hidden int libxl__wait_for_device_model(libxl__gc *gc,
                                 uint32_t domid, char *state,
-                                libxl__device_model_starting *starting,
+                                libxl__spawn_starting *spawning,
                                 int (*check_callback)(libxl__gc *gc,
                                                       uint32_t domid,
                                                       const char *state,