components/library/openssl/openssl-1.0.2/patches/208-CVE-2022-0778.patch

   1 From 3118eb64934499d93db3230748a452351d1d9a65 Mon Sep 17 00:00:00 2001
   2 From: Tomas Mraz <tomas@openssl.org>
   3 Date: Mon, 28 Feb 2022 18:26:21 +0100
   4 Subject: [PATCH] Fix possible infinite loop in BN_mod_sqrt()
   5
   6 The calculation in some cases does not finish for non-prime p.
   7
   8 This fixes CVE-2022-0778.
   9
  10 Based on patch by David Benjamin <davidben@google.com>.
  11
  12 Reviewed-by: Paul Dale <pauli@openssl.org>
  13 Reviewed-by: Matt Caswell <matt@openssl.org>
  14 ---
  15  crypto/bn/bn_sqrt.c | 30 ++++++++++++++++++------------
  16  1 file changed, 18 insertions(+), 12 deletions(-)
  17
  18 diff --git a/crypto/bn/bn_sqrt.c b/crypto/bn/bn_sqrt.c
  19 index 1723d5ded5a8..53b0f559855c 100644
  20 --- a/crypto/bn/bn_sqrt.c
  21 +++ b/crypto/bn/bn_sqrt.c
  22 @@ -14,7 +14,8 @@ BIGNUM *BN_mod_sqrt(BIGNUM *in, const BIGNUM *a, const BIGNUM *p, BN_CTX *ctx)
  23  /*
  24   * Returns 'ret' such that ret^2 == a (mod p), using the Tonelli/Shanks
  25   * algorithm (cf. Henri Cohen, "A Course in Algebraic Computational Number
  26 - * Theory", algorithm 1.5.1). 'p' must be prime!
  27 + * Theory", algorithm 1.5.1). 'p' must be prime, otherwise an error or
  28 + * an incorrect "result" will be returned.
  29   */
  30  {
  31      BIGNUM *ret = in;
  32 @@ -301,18 +302,23 @@ BIGNUM *BN_mod_sqrt(BIGNUM *in, const BIGNUM *a, const BIGNUM *p, BN_CTX *ctx)
  33              goto vrfy;
  34          }
  35
  36 -        /* find smallest  i  such that  b^(2^i) = 1 */
  37 -        i = 1;
  38 -        if (!BN_mod_sqr(t, b, p, ctx))
  39 -            goto end;
  40 -        while (!BN_is_one(t)) {
  41 -            i++;
  42 -            if (i == e) {
  43 -                BNerr(BN_F_BN_MOD_SQRT, BN_R_NOT_A_SQUARE);
  44 -                goto end;
  45 +        /* Find the smallest i, 0 < i < e, such that b^(2^i) = 1. */
  46 +        for (i = 1; i < e; i++) {
  47 +            if (i == 1) {
  48 +                if (!BN_mod_sqr(t, b, p, ctx))
  49 +                    goto end;
  50 +
  51 +            } else {
  52 +                if (!BN_mod_mul(t, t, t, p, ctx))
  53 +                    goto end;
  54              }
  55 -            if (!BN_mod_mul(t, t, t, p, ctx))
  56 -                goto end;
  57 +            if (BN_is_one(t))
  58 +                break;
  59 +        }
  60 +        /* If not found, a is not a square or p is not prime. */
  61 +        if (i >= e) {
  62 +            BNerr(BN_F_BN_MOD_SQRT, BN_R_NOT_A_SQUARE);
  63 +            goto end;
  64          }
  65
  66          /* t := y^2^(e - i - 1) */