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Fix incorrect return check of BN_bn2binpad #16942

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Fix incorrect return check of BN_bn2binpad #16942

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7aaadc6
Fix incorrect return check of BN_bn2binpad
PeiweiHu Nov 1, 2021
63dccef
=0 is valid
PeiweiHu Nov 1, 2021
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2 changes: 1 addition & 1 deletion crypto/ec/ec_deprecated.c
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Original file line number Diff line number Diff line change
Expand Up @@ -52,7 +52,7 @@ EC_POINT *EC_POINT_bn2point(const EC_GROUP *group,
return NULL;
}

if (!BN_bn2binpad(bn, buf, buf_len)) {
if (BN_bn2binpad(bn, buf, buf_len) < 0) {
OPENSSL_free(buf);
return NULL;
}
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2 changes: 1 addition & 1 deletion test/acvp_test.c
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Expand Up @@ -71,7 +71,7 @@ static int pkey_get_bn_bytes(EVP_PKEY *pkey, const char *name,
buf = OPENSSL_zalloc(sz);
if (buf == NULL)
goto err;
if (!BN_bn2binpad(bn, buf, sz))
if (BN_bn2binpad(bn, buf, sz) <= 0)
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Same problem here

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I changed to <= according to reutrn values check in /test/acvp_test.c:229, 231, 570, 572. There are a lot. Do we need to change them all?

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And /crypto/ec/ec_curve.c: 3404

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Same problem here

Hmm, @kroeckx but what the returned 0 indicates? A 0 byte sized number does not look like a number. Perhaps 0 cannot be returned at all? A zero BIGNUM should be encoded as a single zero byte, shouldn't it? So the return value should be 1.

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It's hard to see how a zero could be returned.

We should nonetheless try to be consistent in the return code handling.

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@PeiweiHu PeiweiHu Nov 2, 2021 •
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In #16943, the code invoking BN_bn2nativepad has a consistent handling way. As for BN_bn2binpad, == -1, <0, and <=0 can be found in codebase. Maybe it's better to unify them.

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Agreed, they should be unified. Not necessary for this PR IMO.

goto err;

*out_len = sz;
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2 changes: 1 addition & 1 deletion test/ecdsatest.c
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Expand Up @@ -46,7 +46,7 @@ static int fbytes(unsigned char *buf, size_t num, ossl_unused const char *name,
|| !TEST_true(BN_hex2bn(&tmp, numbers[fbytes_counter]))
/* tmp might need leading zeros so pad it out */
|| !TEST_int_le(BN_num_bytes(tmp), num)
|| !TEST_true(BN_bn2binpad(tmp, buf, num)))
|| !TEST_int_gt(BN_bn2binpad(tmp, buf, num), 0))
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Same problem here

goto err;

fbytes_counter = (fbytes_counter + 1) % OSSL_NELEM(numbers);
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