Medium· 5.3PYSEC-2025-201 CVE-2025-46152Published Sep 25, 2025

In PyTorch before 2.7.0, bitwise_right_shift produces incorrect output for certain out-of-bounds values of the "other" argument.

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Affected versions

2.6.0 → fixed in 2.7.0

Details

The fix

Update

leslie-fang-intel· Dec 20, 2024, 07:03 AM+66−1921270f31e7

test/inductor/test_cpu_repro.py+18 −0

@@ -2281,6 +2281,24 @@ def test_bitwise_right_shift(self):
         res = cfn(x, bit_num)
         self.assertEqual(res_aten_eager, res)
  
+    def test_bitwise_shift_right_corner_inputs(self):
+        # Fix https://github.com/pytorch/pytorch/issues/143555
+        x = torch.tensor(1000, dtype=torch.int64)
+        bit_num = torch.tensor(64, dtype=torch.int64)
+        res_aten_eager = torch.bitwise_right_shift(x, bit_num)
+        cfn = torch.compile(torch.bitwise_right_shift)
+        res = cfn(x, bit_num)
+        self.assertEqual(res_aten_eager, res)
+ 
+    def test_bitwise_shift_left_corner_inputs(self):
+        # Fix https://github.com/pytorch/pytorch/issues/143555
+        x = torch.tensor(1000, dtype=torch.int64)
+        bit_num = torch.tensor(64, dtype=torch.int64)
+        res_aten_eager = torch.bitwise_left_shift(x, bit_num)
+        cfn = torch.compile(torch.bitwise_left_shift)
+        res = cfn(x, bit_num)
+        self.assertEqual(res_aten_eager, res)
+ 
     def test_view_dtype(self):
         def f(x):
             return x.view(torch.int32) >> 2

torch/_inductor/codegen/cpp.py+32 −2

@@ -973,11 +973,41 @@ def bitwise_xor(a, b):
  
     @staticmethod
     def bitwise_left_shift(a, b):
-        return f"decltype({a})({a} << {b})"
+        code = BracesBuffer()
+        code.writeline("[&]()")
+        with code.indent():
+            scalar_t = DTYPE_TO_CPP[a.dtype]
+            code.writeline(
+                f"constexpr decltype({b}) max_shift = sizeof({scalar_t}) * CHAR_BIT;"
+            )
+            code.writeline(
+                f"if ((static_cast<std::make_signed_t<{scalar_t}>>({b}) < 0) || ({b} >= max_shift))"
+            )
+            with code.indent():
+                code.writeline(f"return decltype({a})(0);")
+            code.writeline(
+                f"return decltype({a})(static_cast<std::make_unsigned_t<{scalar_t}>>({a}) << {b});"
+            )
+        code.writeline("()")
+        return code
  
     @staticmethod
     def bitwise_right_shift(a, b):
-        return f"decltype({a})({a} >> {b})"
+        code = BracesBuffer()
+        code.writeline("[&]()")
+        with code.indent():
+            scalar_t = DTYPE_TO_CPP[a.dtype]
+            code.writeline(
+                f"constexpr decltype({b}) max_shift = sizeof({scalar_t}) * CHAR_BIT - std::is_signed_v<{scalar_t}>;"
+            )
+            code.writeline(
+                f"if ((static_cast<std::make_signed_t<{scalar_t}>>({b}) < 0) || ({b} >= max_shift))"
+            )
+            with code.indent():
+                code.writeline(f"return decltype({a})({a} >> max_shift);")
+            code.writeline(f"return decltype({a})({a} >> {b});")
+        code.writeline("()")
+        return code
  
     @staticmethod
     def rand(seed: sympy.Expr, offset: sympy.Expr):
 test/inductor/test_cpu_repro.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

test/inductor/test_cpu_repro.py+1 −1

@@ -2291,7 +2291,7 @@ def test_bitwise_shift_right_corner_inputs(self):
         self.assertEqual(res_aten_eager, res)
  
     def test_bitwise_shift_left_corner_inputs(self):
-        # Fix https://github.com/pytorch/pytorch/issues/143555
+        # Fix https://github.com/pytorch/pytorch/issues/143566
         x = torch.tensor(1000, dtype=torch.int64)
         bit_num = torch.tensor(64, dtype=torch.int64)
         res_aten_eager = torch.bitwise_left_shift(x, bit_num)
 test/inductor/test_cpu_repro.py | 31 +++++++++++++++----------------
 1 file changed, 15 insertions(+), 16 deletions(-)

test/inductor/test_cpu_repro.py+15 −16

@@ -2281,23 +2281,22 @@ def test_bitwise_right_shift(self):
         res = cfn(x, bit_num)
         self.assertEqual(res_aten_eager, res)
  
-    def test_bitwise_shift_right_corner_inputs(self):
+    def test_bitwise_shift_corner_inputs(self):
         # Fix https://github.com/pytorch/pytorch/issues/143555
-        x = torch.tensor(1000, dtype=torch.int64)
-        bit_num = torch.tensor(64, dtype=torch.int64)
-        res_aten_eager = torch.bitwise_right_shift(x, bit_num)
-        cfn = torch.compile(torch.bitwise_right_shift)
-        res = cfn(x, bit_num)
-        self.assertEqual(res_aten_eager, res)
- 
-    def test_bitwise_shift_left_corner_inputs(self):
-        # Fix https://github.com/pytorch/pytorch/issues/143566
-        x = torch.tensor(1000, dtype=torch.int64)
-        bit_num = torch.tensor(64, dtype=torch.int64)
-        res_aten_eager = torch.bitwise_left_shift(x, bit_num)
-        cfn = torch.compile(torch.bitwise_left_shift)
-        res = cfn(x, bit_num)
-        self.assertEqual(res_aten_eager, res)
+        # and https://github.com/pytorch/pytorch/issues/143566
+        bitwise_fns = (
+            torch.bitwise_left_shift,
+            torch.bitwise_right_shift,
+        )
+        for bitwise_fn in bitwise_fns:
+            torch._dynamo.reset()
+            metrics.reset()
+            x = torch.tensor(1000, dtype=torch.int64)
+            bit_num = torch.tensor(64, dtype=torch.int64)
+            res_aten_eager = bitwise_fn(x, bit_num)
+            cfn = torch.compile(bitwise_fn)
+            res = cfn(x, bit_num)
+            self.assertEqual(res_aten_eager, res)
  
     def test_view_dtype(self):
         def f(x):

In PyTorch before 2.7.0, bitwise_right_shift produces incorrect output for certain out-of-bounds values of the "other" argument.

Affected versions

Details

The fix

References