File openssl-CVE-2022-0778.patch of Package openssl-1_1.26614
From 72082ae738bbfdc552a0af55320cdc3c6fe16e1a Mon Sep 17 00:00:00 2001
From: Tomas Mraz <tomas@openssl.org>
Date: Mon, 28 Feb 2022 18:26:21 +0100
Subject: [PATCH] Fix possible infinite loop in BN_mod_sqrt()
The calculation in some cases does not finish for non-prime p.
This fixes CVE-2022-0778.
Based on patch by David Benjamin <davidben@google.com>.
---
crypto/bn/bn_sqrt.c | 30 ++++++++++++++++++------------
1 file changed, 18 insertions(+), 12 deletions(-)
diff --git a/crypto/bn/bn_sqrt.c b/crypto/bn/bn_sqrt.c
index 1723d5ded5..53b0f55985 100644
--- a/crypto/bn/bn_sqrt.c
+++ b/crypto/bn/bn_sqrt.c
@@ -14,7 +14,8 @@ BIGNUM *BN_mod_sqrt(BIGNUM *in, const BIGNUM *a, const BIGNUM *p, BN_CTX *ctx)
/*
* 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;
@@ -301,18 +302,23 @@ BIGNUM *BN_mod_sqrt(BIGNUM *in, const BIGNUM *a, const BIGNUM *p, BN_CTX *ctx)
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) */