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gh-146287: Fix signed/unsigned mismatch in _hashlib_hmac_digest_size #148407

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Merged
gpshead merged 2 commits into from
Apr 12, 2026
+11 −6
Merged

gh-146287: Fix signed/unsigned mismatch in _hashlib_hmac_digest_size #148407

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gh-146287: use signed type for HMAC digest size to prevent unsigned w…
gpshead Apr 11, 2026
1bb2b53
remove overzealous assert.
gpshead Apr 11, 2026
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17 changes: 11 additions & 6 deletions Modules/_hashopenssl.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1006,6 +1006,7 @@ _hashlib_HASH_get_blocksize(PyObject *op, void *Py_UNUSED(closure))
{
HASHobject *self = HASHobject_CAST(op);
long block_size = EVP_MD_CTX_block_size(self->ctx);
assert(block_size > 0);
return PyLong_FromLong(block_size);
}

Expand All @@ -1014,6 +1015,7 @@ _hashlib_HASH_get_digestsize(PyObject *op, void *Py_UNUSED(closure))
{
HASHobject *self = HASHobject_CAST(op);
long size = EVP_MD_CTX_size(self->ctx);
assert(size > 0);
return PyLong_FromLong(size);
}

Expand Down Expand Up @@ -2200,7 +2202,7 @@ _hashlib_hmac_new_impl(PyObject *module, Py_buffer *key, PyObject *msg_obj,
*
* On error, set an exception and return BAD_DIGEST_SIZE.
*/
static unsigned int
static int
_hashlib_hmac_digest_size(HMACobject *self)
{
assert(EVP_MAX_MD_SIZE < INT_MAX);
Expand All @@ -2215,15 +2217,18 @@ _hashlib_hmac_digest_size(HMACobject *self)
}
int digest_size = EVP_MD_size(md);
/* digest_size < 0 iff EVP_MD context is NULL (which is impossible here) */
assert(digest_size >= 0);
assert(digest_size <= (int)EVP_MAX_MD_SIZE);
if (digest_size < 0) {
raise_ssl_error(PyExc_SystemError, "invalid digest size");
return BAD_DIGEST_SIZE;
}
#endif
/* digest_size == 0 means that the context is not entirely initialized */
if (digest_size == 0) {
raise_ssl_error(PyExc_ValueError, "missing digest size");
raise_ssl_error(PyExc_SystemError, "missing digest size");
return BAD_DIGEST_SIZE;
}
return (unsigned int)digest_size;
return (int)digest_size;
}

static int
Expand Down Expand Up @@ -2321,7 +2326,7 @@ _hashlib_HMAC_update_impl(HMACobject *self, PyObject *msg)
static Py_ssize_t
_hmac_digest(HMACobject *self, unsigned char *buf)
{
unsigned int digest_size = _hashlib_hmac_digest_size(self);
int digest_size = _hashlib_hmac_digest_size(self);
assert(digest_size <= EVP_MAX_MD_SIZE);
if (digest_size == BAD_DIGEST_SIZE) {
assert(PyErr_Occurred());
Expand Down Expand Up @@ -2386,7 +2391,7 @@ static PyObject *
_hashlib_hmac_get_digest_size(PyObject *op, void *Py_UNUSED(closure))
{
HMACobject *self = HMACobject_CAST(op);
unsigned int size = _hashlib_hmac_digest_size(self);
int size = _hashlib_hmac_digest_size(self);
return size == BAD_DIGEST_SIZE ? NULL : PyLong_FromLong(size);
}

Expand Down
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