Fix CUDA illegal memory access issues in speculative decoding (#10892)

python/sglang/srt/speculative/eagle_draft_cuda_graph_runner.py

@@ -302,6 +302,7 @@ class EAGLEDraftCudaGraphRunner:
         if bs != raw_bs:
             self.seq_lens.fill_(self.seq_len_fill_value)
             self.out_cache_loc.zero_()
+            self.positions.zero_()
 
         num_tokens = bs * self.num_tokens_per_bs
 

python/sglang/srt/speculative/eagle_draft_extend_cuda_graph_runner.py

@@ -332,6 +332,7 @@ class EAGLEDraftExtendCudaGraphRunner:
         if bs * self.num_tokens_per_bs != num_tokens:
             self.seq_lens.fill_(self.seq_len_fill_value)
             self.out_cache_loc.zero_()
+            self.positions.zero_()
             self.accept_length.fill_(1)
             self.extend_seq_lens.fill_(1)