xl: Fix invalid return of libxl-internal pointers via libxl_domid_to_name()

libxl_domid_to_name has numerous in-and-out-of-library callers. In
library callers now use _libxl_domid_to_name() which participates in
garbage collection and out-of-library callers are fixed up to free() the
domain name.

Signed-off-by: Gianni Tedesco <gianni.tedesco@citrix.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

5 files changed, 50 insertions, 27 deletions

diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index 6d9869be70..3f08f85394 100644
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -1379,7 +1379,7 @@ static int libxl_create_stubdom(libxl_ctx *ctx,
 
     memset(&c_info, 0x00, sizeof(libxl_domain_create_info));
     c_info.hvm = 0;
-    c_info.name = libxl_sprintf(ctx, "%s-dm", libxl_domid_to_name(ctx, info->domid));
+    c_info.name = libxl_sprintf(ctx, "%s-dm", _libxl_domid_to_name(ctx, info->domid));
     for (i = 0; i < 16; i++)
         c_info.uuid[i] = info->uuid[i];
 
@@ -2186,7 +2186,7 @@ retry_transaction:
     flexarray_set(back, boffset++, "state");
     flexarray_set(back, boffset++, libxl_sprintf(ctx, "%d", 1));
     flexarray_set(back, boffset++, "domain");
-    flexarray_set(back, boffset++, libxl_domid_to_name(ctx, domid));
+    flexarray_set(back, boffset++, _libxl_domid_to_name(ctx, domid));
     flexarray_set(back, boffset++, "protocol");
     flexarray_set(back, boffset++, LIBXL_XENCONSOLE_PROTOCOL);
 
@@ -2243,7 +2243,7 @@ int libxl_device_vkb_add(libxl_ctx *ctx, uint32_t domid, libxl_device_vkb *vkb)
     flexarray_set(back, boffset++, "state");
     flexarray_set(back, boffset++, libxl_sprintf(ctx, "%d", 1));
     flexarray_set(back, boffset++, "domain");
-    flexarray_set(back, boffset++, libxl_domid_to_name(ctx, domid));
+    flexarray_set(back, boffset++, _libxl_domid_to_name(ctx, domid));
 
     flexarray_set(front, foffset++, "backend-id");
     flexarray_set(front, foffset++, libxl_sprintf(ctx, "%d", vkb->backend_domid));
@@ -2420,7 +2420,7 @@ static int libxl_build_xenpv_qemu_args(libxl_ctx *ctx,
         uint32_t guest_domid;
         if (libxl_is_stubdom(ctx, vfb->domid, &guest_domid)) {
             char *filename;
-            char *name = libxl_sprintf(ctx, "qemu-dm-%s", libxl_domid_to_name(ctx, guest_domid));
+            char *name = libxl_sprintf(ctx, "qemu-dm-%s", _libxl_domid_to_name(ctx, guest_domid));
             libxl_create_logfile(ctx, name, &filename);
             info->serial = libxl_sprintf(ctx, "file:%s", filename);
             free(filename);
@@ -2438,7 +2438,7 @@ static int libxl_build_xenpv_qemu_args(libxl_ctx *ctx,
         info->extra[j] = NULL;
     }
     info->domid = vfb->domid;
-    info->dom_name = libxl_domid_to_name(ctx, vfb->domid);
+    info->dom_name = _libxl_domid_to_name(ctx, vfb->domid);
     info->device_model = libxl_abs_path(ctx, "qemu-dm", libxl_libexec_path());
     info->type = XENPV;
     return 0;
@@ -2484,7 +2484,7 @@ int libxl_device_vfb_add(libxl_ctx *ctx, uint32_t domid, libxl_device_vfb *vfb)
     flexarray_set(back, boffset++, "state");
     flexarray_set(back, boffset++, libxl_sprintf(ctx, "%d", 1));
     flexarray_set(back, boffset++, "domain");
-    flexarray_set(back, boffset++, libxl_domid_to_name(ctx, domid));
+    flexarray_set(back, boffset++, _libxl_domid_to_name(ctx, domid));
     flexarray_set(back, boffset++, "vnc");
     flexarray_set(back, boffset++, libxl_sprintf(ctx, "%d", vfb->vnc));
     flexarray_set(back, boffset++, "vnclisten");
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 401f812ff7..2b2d9635bc 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -227,8 +227,7 @@ char *libxl_abs_path(libxl_ctx *ctx, char *s, const char *path);
 #define XL_LOG_WARNING XTL_WARN
 #define XL_LOG_ERROR   XTL_ERROR
 
-/* Error handling */
-int libxl_xc_error(int xc_err);
+char *_libxl_domid_to_name(libxl_ctx *ctx, uint32_t domid);
 
 #endif
 
diff --git a/tools/libxl/libxl_pci.c b/tools/libxl/libxl_pci.c
index 41dba62572..9fc605a261 100644
--- a/tools/libxl/libxl_pci.c
+++ b/tools/libxl/libxl_pci.c
@@ -228,7 +228,7 @@ static int libxl_create_pci_backend(libxl_ctx *ctx, uint32_t domid, libxl_device
     flexarray_set(back, boffset++, "state");
     flexarray_set(back, boffset++, libxl_sprintf(ctx, "%d", 1));
     flexarray_set(back, boffset++, "domain");
-    flexarray_set(back, boffset++, libxl_domid_to_name(ctx, domid));
+    flexarray_set(back, boffset++, _libxl_domid_to_name(ctx, domid));
     for (i = 0; i < num; i++) {
         flexarray_set(back, boffset++, libxl_sprintf(ctx, "key-%d", i));
         flexarray_set(back, boffset++, libxl_sprintf(ctx, PCI_BDF, pcidev->domain, pcidev->bus, pcidev->dev, pcidev->func));
diff --git a/tools/libxl/libxl_utils.c b/tools/libxl/libxl_utils.c
index 1042cc848c..7fe10396fc 100644
--- a/tools/libxl/libxl_utils.c
+++ b/tools/libxl/libxl_utils.c
@@ -51,7 +51,14 @@ char *libxl_domid_to_name(libxl_ctx *ctx, uint32_t domid)
 
     snprintf(path, sizeof(path), "/local/domain/%d/name", domid);
     s = xs_read(ctx->xsh, XBT_NULL, path, &len);
-    libxl_ptr_add(ctx, s);
+    return s;
+}
+
+char *_libxl_domid_to_name(libxl_ctx *ctx, uint32_t domid)
+{
+    char *s = libxl_domid_to_name(ctx, domid);
+    if ( s )
+        libxl_ptr_add(ctx, s);
     return s;
 }
 
@@ -68,7 +75,7 @@ int libxl_name_to_domid(libxl_ctx *ctx, const char *name,
         return ERROR_NOMEM;
 
     for (i = 0; i < nb_domains; i++) {
-        domname = libxl_domid_to_name(ctx, dominfo[i].domid);
+        domname = _libxl_domid_to_name(ctx, dominfo[i].domid);
         if (!domname)
             continue;
         if (strcmp(domname, name) == 0) {
diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index ab794d547b..c99c495dfe 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -2154,8 +2154,10 @@ void list_domains(int verbose, const libxl_dominfo *info, int nb_domain)
 
     printf("Name                                        ID   Mem VCPUs\tState\tTime(s)\n");
     for (i = 0; i < nb_domain; i++) {
+        char *domname;
+        domname = libxl_domid_to_name(&ctx, info[i].domid);
         printf("%-40s %5d %5lu %5d     %c%c%c%c%c%c  %8.1f",
-                libxl_domid_to_name(&ctx, info[i].domid),
+                domname,
                 info[i].domid,
                 (unsigned long) (info[i].max_memkb / 1024),
                 info[i].vcpu_online,
@@ -2166,6 +2168,7 @@ void list_domains(int verbose, const libxl_dominfo *info, int nb_domain)
                 info[i].shutdown_reason == SHUTDOWN_crash ? 'c' : '-',
                 info[i].dying ? 'd' : '-',
                 ((float)info[i].cpu_time / 1e9));
+        free(domname);
         if (verbose) {
             char *uuid = libxl_uuid2string(&ctx, info[i].uuid);
             printf(" %s", uuid);
@@ -2177,6 +2180,7 @@ void list_domains(int verbose, const libxl_dominfo *info, int nb_domain)
 void list_vm(void)
 {
     libxl_vminfo *info;
+    char *domname;
     int nb_vm, i;
 
     info = libxl_list_vm(&ctx, &nb_vm);
@@ -2187,12 +2191,14 @@ void list_vm(void)
     }
     printf("UUID                                  ID    name\n");
     for (i = 0; i < nb_vm; i++) {
+        domname = libxl_domid_to_name(&ctx, info[i].domid);
         printf(UUID_FMT "  %d    %-30s\n",
             info[i].uuid[0], info[i].uuid[1], info[i].uuid[2], info[i].uuid[3],
             info[i].uuid[4], info[i].uuid[5], info[i].uuid[6], info[i].uuid[7],
             info[i].uuid[8], info[i].uuid[9], info[i].uuid[10], info[i].uuid[11],
             info[i].uuid[12], info[i].uuid[13], info[i].uuid[14], info[i].uuid[15],
-            info[i].domid, libxl_domid_to_name(&ctx, info[i].domid));
+            info[i].domid, domname);
+        free(domname);
     }
     free(info);
 }
@@ -3197,10 +3203,13 @@ static void print_vcpuinfo(uint32_t tdomid,
     int i, l;
     uint64_t *cpumap;
     uint64_t pcpumap;
+    char *domname;
 
     /*      NAME  ID  VCPU */
+    domname = libxl_domid_to_name(&ctx, tdomid);
     printf("%-32s %5u %5u",
-           libxl_domid_to_name(&ctx, tdomid), tdomid, vcpuinfo->vcpuid);
+           domname, tdomid, vcpuinfo->vcpuid);
+    free(domname);
     if (!vcpuinfo->online) {
         /*      CPU STA */
         printf("%5c %3c%cp ", '-', '-', '-');
@@ -3608,11 +3617,14 @@ static int sched_credit_domain_set(
 static void sched_credit_domain_output(
     int domid, libxl_sched_credit *scinfo)
 {
+    char *domname;
+    domname = libxl_domid_to_name(&ctx, domid);
     printf("%-33s %4d %6d %4d\n",
-        libxl_domid_to_name(&ctx, domid),
+        domname,
         domid,
         scinfo->weight,
         scinfo->cap);
+    free(domname);
 }
 
 int main_sched_credit(int argc, char **argv)
@@ -3758,6 +3770,7 @@ int main_domname(int argc, char **argv)
     }
 
     printf("%s\n", domname);
+    free(domname);
 
     return 0;
 }
@@ -4519,6 +4532,7 @@ static void print_dom0_uptime(int short_mode, time_t now)
     uint32_t uptime = 0;
     char *uptime_str = NULL;
     char *now_str = NULL;
+    char *domname;
 
     fd = open("/proc/uptime", O_RDONLY);
     if (fd == -1)
@@ -4533,24 +4547,25 @@ static void print_dom0_uptime(int short_mode, time_t now)
     strtok(buf, " ");
     uptime = strtoul(buf, NULL, 10);
 
+    domname = libxl_domid_to_name(&ctx, 0);
     if (short_mode)
     {
         now_str = current_time_to_string(now);
         uptime_str = uptime_to_string(uptime, 1);
         printf(" %s up %s, %s (%d)\n", now_str, uptime_str,
-               libxl_domid_to_name(&ctx, 0), 0);
+               domname, 0);
     }
     else
     {
+        now_str = NULL;
         uptime_str = uptime_to_string(uptime, 0);
-        printf("%-33s %4d %s\n", libxl_domid_to_name(&ctx, 0),
+        printf("%-33s %4d %s\n", domname,
                0, uptime_str);
     }
 
-    if (now_str)
-        free(now_str);
-    if (uptime_str)
-        free(uptime_str);
+    free(now_str);
+    free(uptime_str);
+    free(domname);
     return;
 err:
     fprintf(stderr, "Can not get Dom0 uptime.\n");
@@ -4563,29 +4578,31 @@ static void print_domU_uptime(uint32_t domuid, int short_mode, time_t now)
     uint32_t uptime = 0;
     char *uptime_str = NULL;
     char *now_str = NULL;
+    char *domname;
 
     s_time = libxl_vm_get_start_time(&ctx, domuid);
     if (s_time == -1)
         return;
     uptime = now - s_time;
+    domname = libxl_domid_to_name(&ctx, domuid);
     if (short_mode)
     {
         now_str = current_time_to_string(now);
         uptime_str = uptime_to_string(uptime, 1);
         printf(" %s up %s, %s (%d)\n", now_str, uptime_str,
-               libxl_domid_to_name(&ctx, domuid), domuid);
+               domname, domuid);
     }
     else
     {
+        now_str = NULL;
         uptime_str = uptime_to_string(uptime, 0);
-        printf("%-33s %4d %s\n", libxl_domid_to_name(&ctx, domuid),
+        printf("%-33s %4d %s\n", domname,
                domuid, uptime_str);
     }
 
-    if (now_str)
-        free(now_str);
-    if (uptime_str)
-        free(uptime_str);
+    free(domname);
+    free(now_str);
+    free(uptime_str);
     return;
 }