Fix command-line parsing in a few respects -- be more

generous about what we accept, avoid stack overflow, and
print the command line during boot (rather useful!).

This should fix the 'lapic' and 'nolapic' boot options.

Signed-off-by: Keir Fraser <keir@xensource.com>

xen/arch/x86/setup.c

@@ -194,7 +194,7 @@ static void percpu_free_unused_areas(void)
 
 void __init __start_xen(multiboot_info_t *mbi)
 {
-    char *cmdline;
+    char __cmdline[] = "", *cmdline = __cmdline;
     struct domain *idle_domain;
     unsigned long _initrd_start = 0, _initrd_len = 0;
     unsigned int initrdidx = 1;
@@ -210,7 +210,8 @@ void __init __start_xen(multiboot_info_t *mbi)
 
     /* Parse the command-line options. */
     if ( (mbi->flags & MBI_CMDLINE) && (mbi->cmdline != 0) )
-        cmdline_parse(__va(mbi->cmdline));
+        cmdline = __va(mbi->cmdline);
+    cmdline_parse(cmdline);
 
     set_current((struct vcpu *)0xfffff000); /* debug sanity */
     set_processor_id(0); /* needed early, for smp_processor_id() */
@@ -228,6 +229,8 @@ void __init __start_xen(multiboot_info_t *mbi)
 
     init_console();
 
+    printf("Command line: %s\n", cmdline);
+
     /* Check that we have at least one Multiboot module. */
     if ( !(mbi->flags & MBI_MODULES) || (mbi->mods_count == 0) )
     {

xen/common/kernel.c

@@ -43,13 +43,19 @@ void cmdline_parse(char *cmdline)
         /* Grab the next whitespace-delimited option. */
         q = opt;
         while ( (*p != ' ') && (*p != '\0') )
-            *q++ = *p++;
+        {
+            if ( (q-opt) < (sizeof(opt)-1) ) /* avoid overflow */
+                *q++ = *p;
+            p++;
+        }
         *q = '\0';
 
         /* Search for value part of a key=value option. */
         optval = strchr(opt, '=');
         if ( optval != NULL )
-            *optval++ = '\0';
+            *optval++ = '\0'; /* nul-terminate the option value */
+        else
+            optval = q;       /* default option value is empty string */
 
         for ( param = &__setup_start; param <= &__setup_end; param++ )
         {
@@ -59,23 +65,18 @@ void cmdline_parse(char *cmdline)
             switch ( param->type )
             {
             case OPT_STR:
-                if ( optval != NULL )
-                {
-                    strncpy(param->var, optval, param->len);
-                    ((char *)param->var)[param->len-1] = '\0';
-                }
+                strncpy(param->var, optval, param->len);
+                ((char *)param->var)[param->len-1] = '\0';
                 break;
             case OPT_UINT:
-                if ( optval != NULL )
-                    *(unsigned int *)param->var =
-                        simple_strtol(optval, (char **)&optval, 0);
+                *(unsigned int *)param->var =
+                    simple_strtol(optval, (char **)&optval, 0);
                 break;
             case OPT_BOOL:
                 *(int *)param->var = 1;
                 break;
             case OPT_CUSTOM:
-                if ( optval != NULL )
-                    ((void (*)(char *))param->var)(optval);
+                ((void (*)(char *))param->var)(optval);
                 break;
             }
         }