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[3.10] bpo-38256: Fix binascii.crc32 large input. (GH-32000) (GH-32013)

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Inputs >= 4GiB to `binascii.crc32(...)` when compiled to use the zlib
crc32 implementation (the norm on POSIX) no longer return the wrong
result.
This commit is contained in:
Gregory P. Smith 2022-03-20 14:46:52 -07:00 • committed by GitHub
parent 94f038cbb2
commit 4c989e19c8
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GPG key ID: 4AEE18F83AFDEB23
3 changed files with 26 additions and 9 deletions
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20
Modules/binascii.c
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@ -1120,16 +1120,20 @@ binascii_crc32_impl(PyObject *module, Py_buffer *data, unsigned int crc)
/*[clinic end generated code: output=52cf59056a78593b input=bbe340bc99d25aa8]*/
#ifdef USE_ZLIB_CRC32
/* This was taken from zlibmodule.c PyZlib_crc32 (but is PY_SSIZE_T_CLEAN) */
/* The same core as zlibmodule.c zlib_crc32_impl. */
{
const Byte *buf;
Py_ssize_t len;
int signed_val;
unsigned char *buf = data->buf;
Py_ssize_t len = data->len;
buf = (Byte*)data->buf;
len = data->len;
signed_val = crc32(crc, buf, len);
return (unsigned int)signed_val & 0xffffffffU;
/* Avoid truncation of length for very large buffers. crc32() takes
length as an unsigned int, which may be narrower than Py_ssize_t. */
while ((size_t)len > UINT_MAX) {
crc = crc32(crc, buf, UINT_MAX);
buf += (size_t) UINT_MAX;
len -= (size_t) UINT_MAX;
}
crc = crc32(crc, buf, (unsigned int)len);
return crc & 0xffffffff;
}
#else /* USE_ZLIB_CRC32 */
{ /* By Jim Ahlstrom; All rights transferred to CNRI */