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| author | Brian Schubert <brianm.schubert@gmail.com> | 2024-09-20 10:08:59 (GMT) |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2024-09-20 10:08:59 (GMT) |
| commit | 63f196090f90cbfe5f698824655f74dea5cb2b29 (patch) | |
| tree | 53673a94db1e9a94bea99f0cc6af3611d910d5a0 | |
| parent | baa3550bc3a119f41cc4eaed5373f9d695208e8e (diff) | |
| download | cpython-63f196090f90cbfe5f698824655f74dea5cb2b29.zip cpython-63f196090f90cbfe5f698824655f74dea5cb2b29.tar.gz cpython-63f196090f90cbfe5f698824655f74dea5cb2b29.tar.bz2 | |
gh-124248: Fix crash in struct when processing 0p fields (#124251)
| -rw-r--r-- | Lib/test/test_struct.py | 9 | ||||
| -rw-r--r-- | Misc/ACKS | 1 | ||||
| -rw-r--r-- | Misc/NEWS.d/next/Library/2024-09-19-11-47-39.gh-issue-124248.g7rufd.rst | 2 | ||||
| -rw-r--r-- | Modules/_struct.c | 19 |
4 files changed, 27 insertions, 4 deletions
diff --git a/Lib/test/test_struct.py b/Lib/test/test_struct.py index 5508cc3..bdbf880 100644 --- a/Lib/test/test_struct.py +++ b/Lib/test/test_struct.py @@ -96,6 +96,13 @@ class StructTest(unittest.TestCase): ('10s', b'helloworld', b'helloworld', b'helloworld', 0), ('11s', b'helloworld', b'helloworld\0', b'helloworld\0', 1), ('20s', b'helloworld', b'helloworld'+10*b'\0', b'helloworld'+10*b'\0', 1), + ('0p', b'helloworld', b'', b'', 1), + ('1p', b'helloworld', b'\x00', b'\x00', 1), + ('2p', b'helloworld', b'\x01h', b'\x01h', 1), + ('10p', b'helloworld', b'\x09helloworl', b'\x09helloworl', 1), + ('11p', b'helloworld', b'\x0Ahelloworld', b'\x0Ahelloworld', 0), + ('12p', b'helloworld', b'\x0Ahelloworld\0', b'\x0Ahelloworld\0', 1), + ('20p', b'helloworld', b'\x0Ahelloworld'+9*b'\0', b'\x0Ahelloworld'+9*b'\0', 1), ('b', 7, b'\7', b'\7', 0), ('b', -7, b'\371', b'\371', 0), ('B', 7, b'\7', b'\7', 0), @@ -339,6 +346,7 @@ class StructTest(unittest.TestCase): def test_p_code(self): # Test p ("Pascal string") code. for code, input, expected, expectedback in [ + ('0p', b'abc', b'', b''), ('p', b'abc', b'\x00', b''), ('1p', b'abc', b'\x00', b''), ('2p', b'abc', b'\x01a', b'a'), @@ -580,6 +588,7 @@ class StructTest(unittest.TestCase): self.check_sizeof('187s', 1) self.check_sizeof('20p', 1) self.check_sizeof('0s', 1) + self.check_sizeof('0p', 1) self.check_sizeof('0c', 0) def test_boundary_error_message(self): @@ -1653,6 +1653,7 @@ Scott Schram Robin Schreiber Chad J. Schroeder Simon-Martin Schroeder +Brian Schubert Christian Schubert Sam Schulenburg Andreas Schwab diff --git a/Misc/NEWS.d/next/Library/2024-09-19-11-47-39.gh-issue-124248.g7rufd.rst b/Misc/NEWS.d/next/Library/2024-09-19-11-47-39.gh-issue-124248.g7rufd.rst new file mode 100644 index 0000000..1bd333f --- /dev/null +++ b/Misc/NEWS.d/next/Library/2024-09-19-11-47-39.gh-issue-124248.g7rufd.rst @@ -0,0 +1,2 @@ +Fixed potential crash when using :mod:`struct` to process zero-width +'Pascal string' fields (``0p``). diff --git a/Modules/_struct.c b/Modules/_struct.c index f744193..2ae5060 100644 --- a/Modules/_struct.c +++ b/Modules/_struct.c @@ -1669,9 +1669,16 @@ s_unpack_internal(PyStructObject *soself, const char *startfrom, if (e->format == 's') { v = PyBytes_FromStringAndSize(res, code->size); } else if (e->format == 'p') { - Py_ssize_t n = *(unsigned char*)res; - if (n >= code->size) - n = code->size - 1; + Py_ssize_t n; + if (code->size == 0) { + n = 0; + } + else { + n = *(unsigned char*)res; + if (n >= code->size) { + n = code->size - 1; + } + } v = PyBytes_FromStringAndSize(res + 1, n); } else { v = e->unpack(state, res, e); @@ -1982,8 +1989,12 @@ s_pack_internal(PyStructObject *soself, PyObject *const *args, int offset, n = PyByteArray_GET_SIZE(v); p = PyByteArray_AS_STRING(v); } - if (n > (code->size - 1)) + if (code->size == 0) { + n = 0; + } + else if (n > (code->size - 1)) { n = code->size - 1; + } if (n > 0) memcpy(res + 1, p, n); if (n > 255) |