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wolfmath: check mpSz in wc_export_int. #10444

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wolfmath: check mpSz in wc_export_int. #10444

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98831c2
wolfmath: check mpSz in wc_export_int.
philljj May 8, 2026
99e5597
wolfmath: check mpSz cleanup.
philljj May 11, 2026
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8 changes: 8 additions & 0 deletions tests/api/test_wolfmath.c
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Original file line number Diff line number Diff line change
Expand Up @@ -193,6 +193,14 @@ int test_wc_export_int(void)
ExpectIntEQ(wc_export_int(&mp, buf, &len, 0, WC_TYPE_HEX_STR), 0);
/* hex version of 1234 is 04D2 and should be 4 digits + 1 null */
ExpectIntEQ(len, 5);
mp_clear(&mp);

/* test mp_int too large for export buf */
len = sizeof(buf);
ExpectIntEQ(mp_init(&mp), MP_OKAY);
ExpectIntEQ(mp_set_bit(&mp, 257), 0);
ExpectIntEQ(wc_export_int(&mp, buf, &len, keySz, WC_TYPE_UNSIGNED_BIN),
WC_NO_ERR_TRACE(BUFFER_E));

mp_clear(&mp);
#endif
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8 changes: 6 additions & 2 deletions wolfcrypt/src/wolfmath.c
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Original file line number Diff line number Diff line change
Expand Up @@ -253,14 +253,18 @@ int wc_export_int(mp_int* mp, byte* buf, word32* len, word32 keySz,
else {
/* for WC_TYPE_UNSIGNED_BIN keySz is used to zero pad.
* The key size is always returned as the size */
int mpSz = 0;
if (*len < keySz) {
*len = keySz;
return BUFFER_E;
}
*len = keySz;
mpSz = mp_unsigned_bin_size(mp);
if (mpSz < 0 || (word32)mpSz > keySz) {
return BUFFER_E;
}
XMEMSET(buf, 0, *len);
err = mp_to_unsigned_bin(mp, buf +
(keySz - (word32)mp_unsigned_bin_size(mp)));
err = mp_to_unsigned_bin(mp, buf + (keySz - mpSz));
}

return err;
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