1 files changed, 23 insertions, 9 deletions

diff --git a/src/crypto/bn/gcd.c b/src/crypto/bn/gcd.c
index 3132c29..e106149 100644
--- a/src/crypto/bn/gcd.c
+++ b/src/crypto/bn/gcd.c
@@ -223,20 +223,23 @@ err:
 }
 
 /* solves ax == 1 (mod n) */
-static BIGNUM *BN_mod_inverse_no_branch(BIGNUM *out, const BIGNUM *a,
-                                        const BIGNUM *n, BN_CTX *ctx);
+static BIGNUM *BN_mod_inverse_no_branch(BIGNUM *out, int *out_no_inverse,
+                                        const BIGNUM *a, const BIGNUM *n,
+                                        BN_CTX *ctx);
 
-BIGNUM *BN_mod_inverse(BIGNUM *out, const BIGNUM *a, const BIGNUM *n,
-                       BN_CTX *ctx) {
+BIGNUM *BN_mod_inverse_ex(BIGNUM *out, int *out_no_inverse, const BIGNUM *a,
+                          const BIGNUM *n, BN_CTX *ctx) {
   BIGNUM *A, *B, *X, *Y, *M, *D, *T, *R = NULL;
   BIGNUM *ret = NULL;
   int sign;
 
   if ((a->flags & BN_FLG_CONSTTIME) != 0 ||
       (n->flags & BN_FLG_CONSTTIME) != 0) {
-    return BN_mod_inverse_no_branch(out, a, n, ctx);
+    return BN_mod_inverse_no_branch(out, out_no_inverse, a, n, ctx);
   }
 
+  *out_no_inverse = 0;
+
   BN_CTX_start(ctx);
   A = BN_CTX_get(ctx);
   B = BN_CTX_get(ctx);
@@ -522,7 +525,8 @@ BIGNUM *BN_mod_inverse(BIGNUM *out, const BIGNUM *a, const BIGNUM *n,
       }
     }
   } else {
-    OPENSSL_PUT_ERROR(BN, BN_mod_inverse, BN_R_NO_INVERSE);
+    *out_no_inverse = 1;
+    OPENSSL_PUT_ERROR(BN, BN_R_NO_INVERSE);
     goto err;
   }
   ret = R;
@@ -535,16 +539,25 @@ err:
   return ret;
 }
 
+BIGNUM *BN_mod_inverse(BIGNUM *out, const BIGNUM *a, const BIGNUM *n,
+                       BN_CTX *ctx) {
+  int no_inverse;
+  return BN_mod_inverse_ex(out, &no_inverse, a, n, ctx);
+}
+
 /* BN_mod_inverse_no_branch is a special version of BN_mod_inverse.
  * It does not contain branches that may leak sensitive information. */
-static BIGNUM *BN_mod_inverse_no_branch(BIGNUM *out, const BIGNUM *a,
-                                        const BIGNUM *n, BN_CTX *ctx) {
+static BIGNUM *BN_mod_inverse_no_branch(BIGNUM *out, int *out_no_inverse,
+                                        const BIGNUM *a, const BIGNUM *n,
+                                        BN_CTX *ctx) {
   BIGNUM *A, *B, *X, *Y, *M, *D, *T, *R = NULL;
   BIGNUM local_A, local_B;
   BIGNUM *pA, *pB;
   BIGNUM *ret = NULL;
   int sign;
 
+  *out_no_inverse = 0;
+
   BN_CTX_start(ctx);
   A = BN_CTX_get(ctx);
   B = BN_CTX_get(ctx);
@@ -682,7 +695,8 @@ static BIGNUM *BN_mod_inverse_no_branch(BIGNUM *out, const BIGNUM *a,
       }
     }
   } else {
-    OPENSSL_PUT_ERROR(BN, BN_mod_inverse_no_branch, BN_R_NO_INVERSE);
+    *out_no_inverse = 1;
+    OPENSSL_PUT_ERROR(BN, BN_R_NO_INVERSE);
     goto err;
   }
   ret = R;