dmar: device scope mem leak fix

Release memory allocated for scope.devices dmar units on various
failure paths and when disabling dmar. Set device count after
sucessfull memory allocation, not before, in device scope parsing function.

Signed-off-by: Elena Ufimtseva <elena.ufimtseva@oracle.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Yang Zhang <yang.z.zhang@intel.com>

xen/drivers/passthrough/vtd/dmar.c

@@ -81,6 +81,15 @@ static int __init acpi_register_rmrr_unit(struct acpi_rmrr_unit *rmrr)
     return 0;
 }
 
+static void scope_devices_free(struct dmar_scope *scope)
+{
+    if ( !scope )
+        return;
+
+    scope->devices_cnt = 0;
+    xfree(scope->devices);
+}
+
 static void __init disable_all_dmar_units(void)
 {
     struct acpi_drhd_unit *drhd, *_drhd;
@@ -90,16 +99,19 @@ static void __init disable_all_dmar_units(void)
     list_for_each_entry_safe ( drhd, _drhd, &acpi_drhd_units, list )
     {
         list_del(&drhd->list);
+        scope_devices_free(&drhd->scope);
         xfree(drhd);
     }
     list_for_each_entry_safe ( rmrr, _rmrr, &acpi_rmrr_units, list )
     {
         list_del(&rmrr->list);
+        scope_devices_free(&rmrr->scope);
         xfree(rmrr);
     }
     list_for_each_entry_safe ( atsr, _atsr, &acpi_atsr_units, list )
     {
         list_del(&atsr->list);
+        scope_devices_free(&atsr->scope);
         xfree(atsr);
     }
 }
@@ -318,13 +330,13 @@ static int __init acpi_parse_dev_scope(
     if ( (cnt = scope_device_count(start, end)) < 0 )
         return cnt;
 
-    scope->devices_cnt = cnt;
     if ( cnt > 0 )
     {
         scope->devices = xzalloc_array(u16, cnt);
         if ( !scope->devices )
             return -ENOMEM;
     }
+    scope->devices_cnt = cnt;
 
     while ( start < end )
     {
@@ -427,7 +439,7 @@ static int __init acpi_parse_dev_scope(
 
  out:
     if ( ret )
-        xfree(scope->devices);
+        scope_devices_free(scope);
 
     return ret;
 }
@@ -542,6 +554,7 @@ acpi_parse_one_drhd(struct acpi_dmar_header *header)
                     "  Workaround BIOS bug: ignore the DRHD due to all "
                     "devices under its scope are not PCI discoverable!\n");
 
+                scope_devices_free(&dmaru->scope);
                 iommu_free(dmaru);
                 xfree(dmaru);
             }
@@ -562,9 +575,11 @@ acpi_parse_one_drhd(struct acpi_dmar_header *header)
 out:
     if ( ret )
     {
+        scope_devices_free(&dmaru->scope);
         iommu_free(dmaru);
         xfree(dmaru);
     }
+
     return ret;
 }
 
@@ -658,6 +673,7 @@ acpi_parse_one_rmrr(struct acpi_dmar_header *header)
                 "  Ignore the RMRR (%"PRIx64", %"PRIx64") due to "
                 "devices under its scope are not PCI discoverable!\n",
                 rmrru->base_address, rmrru->end_address);
+            scope_devices_free(&rmrru->scope);
             xfree(rmrru);
         }
         else if ( base_addr > end_addr )
@@ -665,6 +681,7 @@ acpi_parse_one_rmrr(struct acpi_dmar_header *header)
             dprintk(XENLOG_WARNING VTDPREFIX,
                 "  The RMRR (%"PRIx64", %"PRIx64") is incorrect!\n",
                 rmrru->base_address, rmrru->end_address);
+            scope_devices_free(&rmrru->scope);
             xfree(rmrru);
             ret = -EFAULT;
         }
@@ -727,7 +744,10 @@ acpi_parse_one_atsr(struct acpi_dmar_header *header)
     }
 
     if ( ret )
+    {
+        scope_devices_free(&atsru->scope);
         xfree(atsru);
+    }
     else
         acpi_register_atsr_unit(atsru);
     return ret;