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Merge bitcoin-core/secp256k1#1218: Update overflow check 

2ef1c9b387 Update overflow check (Russell O'Connor)

Pull request description:

  One does not simply check for integer overlow.

ACKs for top commit:
  sipa:
    ACK 2ef1c9b387
  real-or-random:
    ACK 2ef1c9b387

Tree-SHA512: 61238b7b59b3840aa04c4c3ff768789eba95d8d9cbd16507b86bae585fe8d077ac1ac234f9d8aea7fa342c7278a30d2d888df3a93d7ab24730e73b682b11a7fe
This commit is contained in:
Tim Ruffing 2023-03-07 09:12:13 +01:00
parent 5757318782 2ef1c9b387
commit 8962fc95bb
No known key found for this signature in database
GPG Key ID: 8C461CCD293F6011
2 changed files with 8 additions and 8 deletions
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8
src/modinv32_impl.h
View File

@ -415,10 +415,10 @@ static void secp256k1_modinv32_update_de_30(secp256k1_modinv32_signed30 *d, secp
VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(d, 9, &modinfo->modulus, 1) < 0); /* d < modulus */
VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(e, 9, &modinfo->modulus, -2) > 0); /* e > -2*modulus */
VERIFY_CHECK(secp256k1_modinv32_mul_cmp_30(e, 9, &modinfo->modulus, 1) < 0); /* e < modulus */
VERIFY_CHECK((labs(u) + labs(v)) >= 0); /* |u|+|v| doesn't overflow */
VERIFY_CHECK((labs(q) + labs(r)) >= 0); /* |q|+|r| doesn't overflow */
VERIFY_CHECK((labs(u) + labs(v)) <= M30 + 1); /* |u|+|v| <= 2^30 */
VERIFY_CHECK((labs(q) + labs(r)) <= M30 + 1); /* |q|+|r| <= 2^30 */
VERIFY_CHECK(labs(v) <= M30 + 1); /* |v| <= 2^30 */
VERIFY_CHECK(labs(u) <= (M30 + 1 - labs(v))); /* |u|+|v| <= 2^30 */
VERIFY_CHECK(labs(r) <= M30 + 1); /* |r| <= 2^30 */
VERIFY_CHECK(labs(q) <= (M30 + 1 - labs(r))); /* |q|+|r| <= 2^30 */
#endif
/* [md,me] start as zero; plus [u,q] if d is negative; plus [v,r] if e is negative. */
sd = d->v[8] >> 31;

8
src/modinv64_impl.h
View File

@ -419,10 +419,10 @@ static void secp256k1_modinv64_update_de_62(secp256k1_modinv64_signed62 *d, secp
VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(d, 5, &modinfo->modulus, 1) < 0); /* d < modulus */
VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(e, 5, &modinfo->modulus, -2) > 0); /* e > -2*modulus */
VERIFY_CHECK(secp256k1_modinv64_mul_cmp_62(e, 5, &modinfo->modulus, 1) < 0); /* e < modulus */
VERIFY_CHECK((secp256k1_modinv64_abs(u) + secp256k1_modinv64_abs(v)) >= 0); /* |u|+|v| doesn't overflow */
VERIFY_CHECK((secp256k1_modinv64_abs(q) + secp256k1_modinv64_abs(r)) >= 0); /* |q|+|r| doesn't overflow */
VERIFY_CHECK((secp256k1_modinv64_abs(u) + secp256k1_modinv64_abs(v)) <= (int64_t)1 << 62); /* |u|+|v| <= 2^62 */
VERIFY_CHECK((secp256k1_modinv64_abs(q) + secp256k1_modinv64_abs(r)) <= (int64_t)1 << 62); /* |q|+|r| <= 2^62 */
VERIFY_CHECK(secp256k1_modinv64_abs(v) <= (int64_t)1 << 62); /* |v| <= 2^62 */
VERIFY_CHECK(secp256k1_modinv64_abs(u) <= (((int64_t)1 << 62) - secp256k1_modinv64_abs(v))); /* |u|+|v| <= 2^62 */
VERIFY_CHECK(secp256k1_modinv64_abs(r) <= (int64_t)1 << 62); /* |r| <= 2^62 */
VERIFY_CHECK(secp256k1_modinv64_abs(q) <= (((int64_t)1 << 62) - secp256k1_modinv64_abs(r))); /* |q|+|r| <= 2^62 */
#endif
/* [md,me] start as zero; plus [u,q] if d is negative; plus [v,r] if e is negative. */
sd = d4 >> 63;