diff -up openssl-1.0.2k/crypto/bn/bn_sqrt.c.cve_2022_0778 openssl-1.0.2k/crypto/bn/bn_sqrt.c
--- openssl-1.0.2k/crypto/bn/bn_sqrt.c.cve_2022_0778 2022-03-23 11:23:25.900783626 +0100
+++ openssl-1.0.2k/crypto/bn/bn_sqrt.c 2022-03-23 11:27:14.447109005 +0100
@@ -64,7 +64,8 @@ BIGNUM *BN_mod_sqrt(BIGNUM *in, const BI
/*
* Returns 'ret' such that ret^2 == a (mod p), using the Tonelli/Shanks
* algorithm (cf. Henri Cohen, "A Course in Algebraic Computational Number
- * Theory", algorithm 1.5.1). 'p' must be prime!
+ * Theory", algorithm 1.5.1). 'p' must be prime, otherwise an error or
+ * an incorrect "result" will be returned.
*/
{
BIGNUM *ret = in;
@@ -350,18 +351,23 @@ BIGNUM *BN_mod_sqrt(BIGNUM *in, const BI
goto vrfy;
}
- /* find smallest i such that b^(2^i) = 1 */
- i = 1;
- if (!BN_mod_sqr(t, b, p, ctx))
- goto end;
- while (!BN_is_one(t)) {
- i++;
- if (i == e) {
- BNerr(BN_F_BN_MOD_SQRT, BN_R_NOT_A_SQUARE);
- goto end;
+ /* Find the smallest i, 0 < i < e, such that b^(2^i) = 1. */
+ for (i = 1; i < e; i++) {
+ if (i == 1) {
+ if (!BN_mod_sqr(t, b, p, ctx))
+ goto end;
+
+ } else {
+ if (!BN_mod_mul(t, t, t, p, ctx))
+ goto end;
}
- if (!BN_mod_mul(t, t, t, p, ctx))
- goto end;
+ if (BN_is_one(t))
+ break;
+ }
+ /* If not found, a is not a square or p is not prime. */
+ if (i >= e) {
+ BNerr(BN_F_BN_MOD_SQRT, BN_R_NOT_A_SQUARE);
+ goto end;
}
/* t := y^2^(e - i - 1) */