Check pointer 'kern->accel_queue_back' for NULL before dereferencing

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Pointer 'kern->accel_queue_back' returned from call to function 'acl_malloc' at line 955 may be NULL and will be dereferenced at line 965

Author: sherry-yuan

src/acl_kernel_if.cpp

@@ -978,6 +978,10 @@ int acl_kernel_if_update(const acl_device_def_autodiscovery_t &devdef,
       return 1;
     }
     kern->accel_queue_back = (int *)acl_malloc(kern->num_accel * sizeof(int));
+    if (!(kern->accel_queue_back)) {
+      ACL_KERNEL_IF_DEBUG_MSG(kern, "Failed to allocate memory for kernel IRQ circular buffer.\n");
+      return 1;
+    }
 
     for (unsigned a = 0; a < kern->num_accel; ++a) {
       unsigned int max_same_accel_launches =