From e59353e32b70fcccd65d829fe8145aa2575821ec Mon Sep 17 00:00:00 2001
From: Frederick Price <rprice@pricemail.ca>
Date: Mon, 8 Apr 2024 19:09:16 -0400
Subject: [PATCH 1/2] CVE-2017-18207 cherry-pick
 3c0a5a7c7ba8fbbc95dd1fe76cd7a1c0ce167371

---
 Lib/aifc.py                                   |  4 ++
 Lib/sunau.py                                  |  2 +
 Lib/test/test_aifc.py                         | 63 ++++++++++++------
 Lib/test/test_sunau.py                        | 39 +++++++++++
 Lib/test/test_wave.py                         | 65 +++++++++++++++++++
 Lib/wave.py                                   | 16 ++++-
 .../2018-03-01-17-49-56.bpo-32056.IlpfgE.rst  |  3 +
 7 files changed, 170 insertions(+), 22 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Library/2018-03-01-17-49-56.bpo-32056.IlpfgE.rst

diff --git a/Lib/aifc.py b/Lib/aifc.py
index 981f8010690e00..d0e5e02fa5ee30 100644
--- a/Lib/aifc.py
+++ b/Lib/aifc.py
@@ -465,6 +465,10 @@ def _read_comm_chunk(self, chunk):
         self._nframes = _read_long(chunk)
         self._sampwidth = (_read_short(chunk) + 7) // 8
         self._framerate = int(_read_float(chunk))
+        if self._sampwidth <= 0:
+            raise Error('bad sample width')
+        if self._nchannels <= 0:
+            raise Error('bad # of channels')
         self._framesize = self._nchannels * self._sampwidth
         if self._aifc:
             #DEBUG: SGI's soundeditor produces a bad size :-(
diff --git a/Lib/sunau.py b/Lib/sunau.py
index b53044d22b1648..b5d83ea4b464c6 100644
--- a/Lib/sunau.py
+++ b/Lib/sunau.py
@@ -194,6 +194,8 @@ def initfp(self, file):
             raise Error, 'unknown encoding'
         self._framerate = int(_read_u32(file))
         self._nchannels = int(_read_u32(file))
+        if not self._nchannels:
+            raise Error('bad # of channels')
         self._framesize = self._framesize * self._nchannels
         if self._hdr_size > 24:
             self._info = file.read(self._hdr_size - 24)
diff --git a/Lib/test/test_aifc.py b/Lib/test/test_aifc.py
index 92bbe7bc75da93..48c20c8b40d94a 100644
--- a/Lib/test/test_aifc.py
+++ b/Lib/test/test_aifc.py
@@ -216,45 +216,70 @@ def test_read_no_comm_chunk(self):
 
     def test_read_no_ssnd_chunk(self):
         b = b'FORM' + struct.pack('>L', 4) + b'AIFC'
-        b += b'COMM' + struct.pack('>LhlhhLL', 38, 0, 0, 0, 0, 0, 0)
+        b += b'COMM' + struct.pack('>LhlhhLL', 38, 1, 0, 8,
+                                   0x4000 | 12, 11025<<18, 0)
         b += b'NONE' + struct.pack('B', 14) + b'not compressed' + b'\x00'
         with self.assertRaisesRegexp(aifc.Error, 'COMM chunk and/or SSND chunk'
                                                  ' missing'):
             aifc.open(io.BytesIO(b))
 
     def test_read_wrong_compression_type(self):
-        b = 'FORM' + struct.pack('>L', 4) + 'AIFC'
-        b += 'COMM' + struct.pack('>LhlhhLL', 23, 0, 0, 0, 0, 0, 0)
-        b += 'WRNG' + struct.pack('B', 0)
+        b = b'FORM' + struct.pack('>L', 4) + b'AIFC'
+        b += b'COMM' + struct.pack('>LhlhhLL', 23, 1, 0, 8,
+                                   0x4000 | 12, 11025<<18, 0)
+        b += b'WRNG' + struct.pack('B', 0)
         self.assertRaises(aifc.Error, aifc.open, io.BytesIO(b))
 
+    def test_read_wrong_number_of_channels(self):
+        for nchannels in 0, -1:
+            b = b'FORM' + struct.pack('>L', 4) + b'AIFC'
+            b += b'COMM' + struct.pack('>LhlhhLL', 38, nchannels, 0, 8,
+                                       0x4000 | 12, 11025<<18, 0)
+            b += b'NONE' + struct.pack('B', 14) + b'not compressed' + b'\x00'
+            b += b'SSND' + struct.pack('>L', 8) + b'\x00' * 8
+            with self.assertRaisesRegex(aifc.Error, 'bad # of channels'):
+                aifc.open(io.BytesIO(b))
+
+    def test_read_wrong_sample_width(self):
+        for sampwidth in 0, -1:
+            b = b'FORM' + struct.pack('>L', 4) + b'AIFC'
+            b += b'COMM' + struct.pack('>LhlhhLL', 38, 1, 0, sampwidth,
+                                       0x4000 | 12, 11025<<18, 0)
+            b += b'NONE' + struct.pack('B', 14) + b'not compressed' + b'\x00'
+            b += b'SSND' + struct.pack('>L', 8) + b'\x00' * 8
+            with self.assertRaisesRegex(aifc.Error, 'bad sample width'):
+                aifc.open(io.BytesIO(b))
+
     def test_read_wrong_marks(self):
-        b = 'FORM' + struct.pack('>L', 4) + 'AIFF'
-        b += 'COMM' + struct.pack('>LhlhhLL', 18, 0, 0, 0, 0, 0, 0)
-        b += 'SSND' + struct.pack('>L', 8) + '\x00' * 8
-        b += 'MARK' + struct.pack('>LhB', 3, 1, 1)
-        with captured_stdout() as s:
+        b = b'FORM' + struct.pack('>L', 4) + b'AIFF'
+        b += b'COMM' + struct.pack('>LhlhhLL', 18, 1, 0, 8,
+                                   0x4000 | 12, 11025<<18, 0)
+        b += b'SSND' + struct.pack('>L', 8) + b'\x00' * 8
+        b += b'MARK' + struct.pack('>LhB', 3, 1, 1)
+        with self.assertWarns(UserWarning) as cm:
             f = aifc.open(io.BytesIO(b))
         self.assertEqual(s.getvalue(), 'Warning: MARK chunk contains '
                                        'only 0 markers instead of 1\n')
         self.assertEqual(f.getmarkers(), None)
 
     def test_read_comm_kludge_compname_even(self):
-        b = 'FORM' + struct.pack('>L', 4) + 'AIFC'
-        b += 'COMM' + struct.pack('>LhlhhLL', 18, 0, 0, 0, 0, 0, 0)
-        b += 'NONE' + struct.pack('B', 4) + 'even' + '\x00'
-        b += 'SSND' + struct.pack('>L', 8) + '\x00' * 8
-        with captured_stdout() as s:
+        b = b'FORM' + struct.pack('>L', 4) + b'AIFC'
+        b += b'COMM' + struct.pack('>LhlhhLL', 18, 1, 0, 8,
+                                   0x4000 | 12, 11025<<18, 0)
+        b += b'NONE' + struct.pack('B', 4) + b'even' + b'\x00'
+        b += b'SSND' + struct.pack('>L', 8) + b'\x00' * 8
+        with self.assertWarns(UserWarning) as cm:
             f = aifc.open(io.BytesIO(b))
         self.assertEqual(s.getvalue(), 'Warning: bad COMM chunk size\n')
         self.assertEqual(f.getcompname(), 'even')
 
     def test_read_comm_kludge_compname_odd(self):
-        b = 'FORM' + struct.pack('>L', 4) + 'AIFC'
-        b += 'COMM' + struct.pack('>LhlhhLL', 18, 0, 0, 0, 0, 0, 0)
-        b += 'NONE' + struct.pack('B', 3) + 'odd'
-        b += 'SSND' + struct.pack('>L', 8) + '\x00' * 8
-        with captured_stdout() as s:
+        b = b'FORM' + struct.pack('>L', 4) + b'AIFC'
+        b += b'COMM' + struct.pack('>LhlhhLL', 18, 1, 0, 8,
+                                   0x4000 | 12, 11025<<18, 0)
+        b += b'NONE' + struct.pack('B', 3) + b'odd'
+        b += b'SSND' + struct.pack('>L', 8) + b'\x00' * 8
+        with self.assertWarns(UserWarning) as cm:
             f = aifc.open(io.BytesIO(b))
         self.assertEqual(s.getvalue(), 'Warning: bad COMM chunk size\n')
         self.assertEqual(f.getcompname(), 'odd')
diff --git a/Lib/test/test_sunau.py b/Lib/test/test_sunau.py
index f6828683521df1..332868c25ff00d 100644
--- a/Lib/test/test_sunau.py
+++ b/Lib/test/test_sunau.py
@@ -1,6 +1,9 @@
 from test.test_support import TESTFN, run_unittest
 import unittest
 from test import audiotests
+from audioop import byteswap
+import io
+import struct
 import sys
 import sunau
 
@@ -96,5 +99,41 @@ def test_main():
     run_unittest(SunauPCM8Test, SunauPCM16Test, SunauPCM16Test,
                  SunauPCM32Test, SunauULAWTest)
 
+
+class SunauLowLevelTest(unittest.TestCase):
+
+    def test_read_bad_magic_number(self):
+        b = b'SPA'
+        with self.assertRaises(EOFError):
+            sunau.open(io.BytesIO(b))
+        b = b'SPAM'
+        with self.assertRaisesRegex(sunau.Error, 'bad magic number'):
+            sunau.open(io.BytesIO(b))
+
+    def test_read_too_small_header(self):
+        b = struct.pack('>LLLLL', sunau.AUDIO_FILE_MAGIC, 20, 0,
+                        sunau.AUDIO_FILE_ENCODING_LINEAR_8, 11025)
+        with self.assertRaisesRegex(sunau.Error, 'header size too small'):
+            sunau.open(io.BytesIO(b))
+
+    def test_read_too_large_header(self):
+        b = struct.pack('>LLLLLL', sunau.AUDIO_FILE_MAGIC, 124, 0,
+                        sunau.AUDIO_FILE_ENCODING_LINEAR_8, 11025, 1)
+        b += b'\0' * 100
+        with self.assertRaisesRegex(sunau.Error, 'header size ridiculously large'):
+            sunau.open(io.BytesIO(b))
+
+    def test_read_wrong_encoding(self):
+        b = struct.pack('>LLLLLL', sunau.AUDIO_FILE_MAGIC, 24, 0, 0, 11025, 1)
+        with self.assertRaisesRegex(sunau.Error, r'encoding not \(yet\) supported'):
+            sunau.open(io.BytesIO(b))
+
+    def test_read_wrong_number_of_channels(self):
+        b = struct.pack('>LLLLLL', sunau.AUDIO_FILE_MAGIC, 24, 0,
+                        sunau.AUDIO_FILE_ENCODING_LINEAR_8, 11025, 0)
+        with self.assertRaisesRegex(sunau.Error, 'bad # of channels'):
+            sunau.open(io.BytesIO(b))
+
+
 if __name__ == "__main__":
     test_main()
diff --git a/Lib/test/test_wave.py b/Lib/test/test_wave.py
index 9513df459386b2..ab911d70a08163 100644
--- a/Lib/test/test_wave.py
+++ b/Lib/test/test_wave.py
@@ -1,6 +1,10 @@
 from test.test_support import TESTFN, run_unittest
 import unittest
 from test import audiotests
+from test import support
+from audioop import byteswap
+import io
+import struct
 import sys
 import wave
 
@@ -119,5 +123,66 @@ def test_unseekable_incompleted_write(self):
 def test_main():
     run_unittest(WavePCM8Test, WavePCM16Test, WavePCM24Test, WavePCM32Test)
 
+
+class WaveLowLevelTest(unittest.TestCase):
+
+    def test_read_no_chunks(self):
+        b = b'SPAM'
+        with self.assertRaises(EOFError):
+            wave.open(io.BytesIO(b))
+
+    def test_read_no_riff_chunk(self):
+        b = b'SPAM' + struct.pack('<L', 0)
+        with self.assertRaisesRegex(wave.Error,
+                                    'file does not start with RIFF id'):
+            wave.open(io.BytesIO(b))
+
+    def test_read_not_wave(self):
+        b = b'RIFF' + struct.pack('<L', 4) + b'SPAM'
+        with self.assertRaisesRegex(wave.Error,
+                                    'not a WAVE file'):
+            wave.open(io.BytesIO(b))
+
+    def test_read_no_fmt_no_data_chunk(self):
+        b = b'RIFF' + struct.pack('<L', 4) + b'WAVE'
+        with self.assertRaisesRegex(wave.Error,
+                                    'fmt chunk and/or data chunk missing'):
+            wave.open(io.BytesIO(b))
+
+    def test_read_no_data_chunk(self):
+        b = b'RIFF' + struct.pack('<L', 28) + b'WAVE'
+        b += b'fmt ' + struct.pack('<LHHLLHH', 16, 1, 1, 11025, 11025, 1, 8)
+        with self.assertRaisesRegex(wave.Error,
+                                    'fmt chunk and/or data chunk missing'):
+            wave.open(io.BytesIO(b))
+
+    def test_read_no_fmt_chunk(self):
+        b = b'RIFF' + struct.pack('<L', 12) + b'WAVE'
+        b += b'data' + struct.pack('<L', 0)
+        with self.assertRaisesRegex(wave.Error, 'data chunk before fmt chunk'):
+            wave.open(io.BytesIO(b))
+
+    def test_read_wrong_form(self):
+        b = b'RIFF' + struct.pack('<L', 36) + b'WAVE'
+        b += b'fmt ' + struct.pack('<LHHLLHH', 16, 2, 1, 11025, 11025, 1, 1)
+        b += b'data' + struct.pack('<L', 0)
+        with self.assertRaisesRegex(wave.Error, 'unknown format: 2'):
+            wave.open(io.BytesIO(b))
+
+    def test_read_wrong_number_of_channels(self):
+        b = b'RIFF' + struct.pack('<L', 36) + b'WAVE'
+        b += b'fmt ' + struct.pack('<LHHLLHH', 16, 1, 0, 11025, 11025, 1, 8)
+        b += b'data' + struct.pack('<L', 0)
+        with self.assertRaisesRegex(wave.Error, 'bad # of channels'):
+            wave.open(io.BytesIO(b))
+
+    def test_read_wrong_sample_width(self):
+        b = b'RIFF' + struct.pack('<L', 36) + b'WAVE'
+        b += b'fmt ' + struct.pack('<LHHLLHH', 16, 1, 1, 11025, 11025, 1, 0)
+        b += b'data' + struct.pack('<L', 0)
+        with self.assertRaisesRegex(wave.Error, 'bad sample width'):
+            wave.open(io.BytesIO(b))
+
+
 if __name__ == '__main__':
     test_main()
diff --git a/Lib/wave.py b/Lib/wave.py
index 28acaa6cb43ec8..189c18e1747f5d 100644
--- a/Lib/wave.py
+++ b/Lib/wave.py
@@ -266,12 +266,22 @@ def readframes(self, nframes):
     #
 
     def _read_fmt_chunk(self, chunk):
-        wFormatTag, self._nchannels, self._framerate, dwAvgBytesPerSec, wBlockAlign = struct.unpack('<HHLLH', chunk.read(14))
+        try:
+            wFormatTag, self._nchannels, self._framerate, dwAvgBytesPerSec, wBlockAlign = struct.unpack_from('<HHLLH', chunk.read(14))
+        except struct.error:
+            raise EOFError from None
         if wFormatTag == WAVE_FORMAT_PCM:
-            sampwidth = struct.unpack('<H', chunk.read(2))[0]
+            try:
+                sampwidth = struct.unpack_from('<H', chunk.read(2))[0]
+            except struct.error:
+                raise EOFError from None
             self._sampwidth = (sampwidth + 7) // 8
+            if not self._sampwidth:
+                raise Error('bad sample width')
         else:
-            raise Error, 'unknown format: %r' % (wFormatTag,)
+            raise Error('unknown format: %r' % (wFormatTag,))
+        if not self._nchannels:
+            raise Error('bad # of channels')
         self._framesize = self._nchannels * self._sampwidth
         self._comptype = 'NONE'
         self._compname = 'not compressed'
diff --git a/Misc/NEWS.d/next/Library/2018-03-01-17-49-56.bpo-32056.IlpfgE.rst b/Misc/NEWS.d/next/Library/2018-03-01-17-49-56.bpo-32056.IlpfgE.rst
new file mode 100644
index 00000000000000..421aa3767794e0
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2018-03-01-17-49-56.bpo-32056.IlpfgE.rst
@@ -0,0 +1,3 @@
+Improved exceptions raised for invalid number of channels and sample width
+when read an audio file in modules :mod:`aifc`, :mod:`wave` and
+:mod:`sunau`.

From b9337f0314f60ab6ddffcea9d7a9ae5ceeea5b74 Mon Sep 17 00:00:00 2001
From: Frederick Price <rprice@pricemail.ca>
Date: Tue, 9 Apr 2024 13:21:39 -0400
Subject: [PATCH 2/2] CVE-2017-18207 Fix up code for Python2

---
 Lib/aifc.py            | 28 ++++++++++++++++------------
 Lib/test/test_aifc.py  | 17 +++++++----------
 Lib/test/test_sunau.py |  1 -
 Lib/test/test_wave.py  |  1 -
 Lib/wave.py            |  4 ++--
 5 files changed, 25 insertions(+), 26 deletions(-)

diff --git a/Lib/aifc.py b/Lib/aifc.py
index d0e5e02fa5ee30..880ad50a48da67 100644
--- a/Lib/aifc.py
+++ b/Lib/aifc.py
@@ -135,6 +135,7 @@
 """
 
 import struct
+import warnings
 import __builtin__
 
 __all__ = ["Error","open","openfp"]
@@ -316,16 +317,16 @@ def initfp(self, file):
             except EOFError:
                 break
             chunkname = chunk.getname()
-            if chunkname == 'COMM':
+            if chunkname == b'COMM':
                 self._read_comm_chunk(chunk)
                 self._comm_chunk_read = 1
-            elif chunkname == 'SSND':
+            elif chunkname == b'SSND':
                 self._ssnd_chunk = chunk
                 dummy = chunk.read(8)
                 self._ssnd_seek_needed = 0
-            elif chunkname == 'FVER':
+            elif chunkname == b'FVER':
                 self._version = _read_ulong(chunk)
-            elif chunkname == 'MARK':
+            elif chunkname == b'MARK':
                 self._readmark(chunk)
             chunk.skip()
         if not self._comm_chunk_read or not self._ssnd_chunk:
@@ -466,16 +467,17 @@ def _read_comm_chunk(self, chunk):
         self._sampwidth = (_read_short(chunk) + 7) // 8
         self._framerate = int(_read_float(chunk))
         if self._sampwidth <= 0:
-            raise Error('bad sample width')
+            raise Error, 'bad sample width'
         if self._nchannels <= 0:
-            raise Error('bad # of channels')
+            raise Error, 'bad # of channels'
+
         self._framesize = self._nchannels * self._sampwidth
         if self._aifc:
             #DEBUG: SGI's soundeditor produces a bad size :-(
             kludge = 0
             if chunk.chunksize == 18:
                 kludge = 1
-                print 'Warning: bad COMM chunk size'
+                warnings.warn("bad COMM chunk size")
                 chunk.chunksize = 23
             #DEBUG end
             self._comptype = chunk.read(4)
@@ -539,11 +541,13 @@ def _readmark(self, chunk):
                     # a position 0 and name ''
                     self._markers.append((id, pos, name))
         except EOFError:
-            print 'Warning: MARK chunk contains only',
-            print len(self._markers),
-            if len(self._markers) == 1: print 'marker',
-            else: print 'markers',
-            print 'instead of', nmarkers
+            warning_message = 'MARK chunk contains only ' + str(len(self._markers))
+            if len(self._markers) == 1: 
+                warning_message += ' marker '
+            else: 
+                warning_message += ' markers '
+            warning_message += 'instead of ' + str(nmarkers)
+            warnings.warn(warning_message)
 
 class Aifc_write:
     # Variables used in this class:
diff --git a/Lib/test/test_aifc.py b/Lib/test/test_aifc.py
index 48c20c8b40d94a..f21798dfe4bc7c 100644
--- a/Lib/test/test_aifc.py
+++ b/Lib/test/test_aifc.py
@@ -7,6 +7,7 @@
 import sys
 import struct
 import aifc
+from test.test_support import check_warnings
 
 
 class AifcTest(audiotests.AudioWriteTests,
@@ -237,7 +238,7 @@ def test_read_wrong_number_of_channels(self):
                                        0x4000 | 12, 11025<<18, 0)
             b += b'NONE' + struct.pack('B', 14) + b'not compressed' + b'\x00'
             b += b'SSND' + struct.pack('>L', 8) + b'\x00' * 8
-            with self.assertRaisesRegex(aifc.Error, 'bad # of channels'):
+            with self.assertRaisesRegexp(aifc.Error, 'bad # of channels'):
                 aifc.open(io.BytesIO(b))
 
     def test_read_wrong_sample_width(self):
@@ -247,7 +248,7 @@ def test_read_wrong_sample_width(self):
                                        0x4000 | 12, 11025<<18, 0)
             b += b'NONE' + struct.pack('B', 14) + b'not compressed' + b'\x00'
             b += b'SSND' + struct.pack('>L', 8) + b'\x00' * 8
-            with self.assertRaisesRegex(aifc.Error, 'bad sample width'):
+            with self.assertRaisesRegexp(aifc.Error, 'bad sample width'):
                 aifc.open(io.BytesIO(b))
 
     def test_read_wrong_marks(self):
@@ -256,11 +257,9 @@ def test_read_wrong_marks(self):
                                    0x4000 | 12, 11025<<18, 0)
         b += b'SSND' + struct.pack('>L', 8) + b'\x00' * 8
         b += b'MARK' + struct.pack('>LhB', 3, 1, 1)
-        with self.assertWarns(UserWarning) as cm:
+        with check_warnings(('MARK chunk contains only 0 markers instead of 1', UserWarning)):
             f = aifc.open(io.BytesIO(b))
-        self.assertEqual(s.getvalue(), 'Warning: MARK chunk contains '
-                                       'only 0 markers instead of 1\n')
-        self.assertEqual(f.getmarkers(), None)
+            self.assertEqual(f.getmarkers(), None)
 
     def test_read_comm_kludge_compname_even(self):
         b = b'FORM' + struct.pack('>L', 4) + b'AIFC'
@@ -268,9 +267,8 @@ def test_read_comm_kludge_compname_even(self):
                                    0x4000 | 12, 11025<<18, 0)
         b += b'NONE' + struct.pack('B', 4) + b'even' + b'\x00'
         b += b'SSND' + struct.pack('>L', 8) + b'\x00' * 8
-        with self.assertWarns(UserWarning) as cm:
+        with check_warnings(('bad COMM chunk size', UserWarning)):
             f = aifc.open(io.BytesIO(b))
-        self.assertEqual(s.getvalue(), 'Warning: bad COMM chunk size\n')
         self.assertEqual(f.getcompname(), 'even')
 
     def test_read_comm_kludge_compname_odd(self):
@@ -279,9 +277,8 @@ def test_read_comm_kludge_compname_odd(self):
                                    0x4000 | 12, 11025<<18, 0)
         b += b'NONE' + struct.pack('B', 3) + b'odd'
         b += b'SSND' + struct.pack('>L', 8) + b'\x00' * 8
-        with self.assertWarns(UserWarning) as cm:
+        with check_warnings(('bad COMM chunk size', UserWarning)):
             f = aifc.open(io.BytesIO(b))
-        self.assertEqual(s.getvalue(), 'Warning: bad COMM chunk size\n')
         self.assertEqual(f.getcompname(), 'odd')
 
     def test_write_params_raises(self):
diff --git a/Lib/test/test_sunau.py b/Lib/test/test_sunau.py
index 332868c25ff00d..1550600495fa78 100644
--- a/Lib/test/test_sunau.py
+++ b/Lib/test/test_sunau.py
@@ -1,7 +1,6 @@
 from test.test_support import TESTFN, run_unittest
 import unittest
 from test import audiotests
-from audioop import byteswap
 import io
 import struct
 import sys
diff --git a/Lib/test/test_wave.py b/Lib/test/test_wave.py
index ab911d70a08163..9d01eacc539a43 100644
--- a/Lib/test/test_wave.py
+++ b/Lib/test/test_wave.py
@@ -2,7 +2,6 @@
 import unittest
 from test import audiotests
 from test import support
-from audioop import byteswap
 import io
 import struct
 import sys
diff --git a/Lib/wave.py b/Lib/wave.py
index 189c18e1747f5d..2d34ae756270db 100644
--- a/Lib/wave.py
+++ b/Lib/wave.py
@@ -269,12 +269,12 @@ def _read_fmt_chunk(self, chunk):
         try:
             wFormatTag, self._nchannels, self._framerate, dwAvgBytesPerSec, wBlockAlign = struct.unpack_from('<HHLLH', chunk.read(14))
         except struct.error:
-            raise EOFError from None
+            raise EOFError
         if wFormatTag == WAVE_FORMAT_PCM:
             try:
                 sampwidth = struct.unpack_from('<H', chunk.read(2))[0]
             except struct.error:
-                raise EOFError from None
+                raise EOFError
             self._sampwidth = (sampwidth + 7) // 8
             if not self._sampwidth:
                 raise Error('bad sample width')