Add range checks to varios ASN1_INTEGER functions to ensure the

sizes used remain a positive integer. Should address issue
13799 from oss-fuzz
ok tb@ jsing@

3 files changed, 62 insertions, 6 deletions

diff --git a/src/lib/libcrypto/asn1/a_int.c b/src/lib/libcrypto/asn1/a_int.c
index 95d0f6dbb2..218d0b607b 100644
--- a/src/lib/libcrypto/asn1/a_int.c
+++ b/src/lib/libcrypto/asn1/a_int.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: a_int.c,v 1.31 2017/01/29 17:49:22 beck Exp $ */
+/* $OpenBSD: a_int.c,v 1.32 2019/03/23 18:48:14 beck Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -59,13 +59,24 @@
 #include <stdio.h>
 #include <string.h>
 
+#include <sys/limits.h>
+
 #include <openssl/asn1.h>
 #include <openssl/bn.h>
 #include <openssl/err.h>
 
+static int
+ASN1_INTEGER_valid(const ASN1_INTEGER *a)
+{
+        return (a != NULL && a->length >= 0);
+}
+
 ASN1_INTEGER *
 ASN1_INTEGER_dup(const ASN1_INTEGER *x)
 {
+        if (!ASN1_INTEGER_valid(x))
+                return NULL;
+
         return ASN1_STRING_dup(x);
 }
 
@@ -123,8 +134,9 @@ i2c_ASN1_INTEGER(ASN1_INTEGER *a, unsigned char **pp)
         int pad = 0, ret, i, neg;
         unsigned char *p, *n, pb = 0;
 
-        if (a == NULL)
-                return (0);
+        if (!ASN1_INTEGER_valid(a))
+                return 0;
+
         neg = a->type & V_ASN1_NEG;
         if (a->length == 0)
                 ret = 1;
@@ -201,11 +213,24 @@ c2i_ASN1_INTEGER(ASN1_INTEGER **a, const unsigned char **pp, long len)
         } else
                 ret = (*a);
 
+        if (!ASN1_INTEGER_valid(ret)) {
+                /*
+                 * XXX using i for an alert is confusing,
+                 * we should call this al
+                 */
+                i = ERR_R_ASN1_LENGTH_MISMATCH;
+                goto err;
+        }
+
         p = *pp;
         pend = p + len;
 
         /* We must malloc stuff, even for 0 bytes otherwise it
          * signifies a missing NULL parameter. */
+        if (len < 0 || len > INT_MAX) {
+                i = ERR_R_ASN1_LENGTH_MISMATCH;
+                goto err;
+        }
         s = malloc(len + 1);
         if (s == NULL) {
                 i = ERR_R_MALLOC_FAILURE;
@@ -294,6 +319,11 @@ d2i_ASN1_UINTEGER(ASN1_INTEGER **a, const unsigned char **pp, long length)
         } else
                 ret = (*a);
 
+        if (!ASN1_INTEGER_valid(ret)) {
+                i = ERR_R_ASN1_LENGTH_MISMATCH;
+                goto err;
+        }
+
         p = *pp;
         inf = ASN1_get_object(&p, &len, &tag, &xclass, length);
         if (inf & 0x80) {
@@ -308,6 +338,10 @@ d2i_ASN1_UINTEGER(ASN1_INTEGER **a, const unsigned char **pp, long length)
 
         /* We must malloc stuff, even for 0 bytes otherwise it
          * signifies a missing NULL parameter. */
+        if (len < 0 || len > INT_MAX) {
+                i = ERR_R_ASN1_LENGTH_MISMATCH;
+                goto err;
+        }
         s = malloc(len + 1);
         if (s == NULL) {
                 i = ERR_R_MALLOC_FAILURE;
@@ -375,6 +409,12 @@ ASN1_INTEGER_set(ASN1_INTEGER *a, long v)
         return (1);
 }
 
+/*
+ * XXX this particular API is a gibbering eidrich horror that makes it
+ * impossible to determine valid return cases from errors.. "a bit
+ * ugly" is preserved for posterity, unfortunately this is probably
+ * unfixable without changing public API
+ */
 long
 ASN1_INTEGER_get(const ASN1_INTEGER *a)
 {
@@ -389,6 +429,9 @@ ASN1_INTEGER_get(const ASN1_INTEGER *a)
         else if (i != V_ASN1_INTEGER)
                 return -1;
 
+        if (!ASN1_INTEGER_valid(a))
+                return -1; /* XXX best effort */
+
         if (a->length > (int)sizeof(long)) {
                 /* hmm... a bit ugly, return all ones */
                 return -1;
@@ -419,6 +462,10 @@ BN_to_ASN1_INTEGER(const BIGNUM *bn, ASN1_INTEGER *ai)
                 ASN1error(ERR_R_NESTED_ASN1_ERROR);
                 goto err;
         }
+
+        if (!ASN1_INTEGER_valid(ret))
+                goto err;
+
         if (BN_is_negative(bn))
                 ret->type = V_ASN1_NEG_INTEGER;
         else
@@ -453,6 +500,9 @@ ASN1_INTEGER_to_BN(const ASN1_INTEGER *ai, BIGNUM *bn)
 {
         BIGNUM *ret;
 
+        if (!ASN1_INTEGER_valid(ai))
+                return (NULL);
+
         if ((ret = BN_bin2bn(ai->data, ai->length, bn)) == NULL)
                 ASN1error(ASN1_R_BN_LIB);
         else if (ai->type == V_ASN1_NEG_INTEGER)
diff --git a/src/lib/libcrypto/asn1/tasn_prn.c b/src/lib/libcrypto/asn1/tasn_prn.c
index b8f7dd5294..9fbf177ba4 100644
--- a/src/lib/libcrypto/asn1/tasn_prn.c
+++ b/src/lib/libcrypto/asn1/tasn_prn.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: tasn_prn.c,v 1.17 2018/04/25 11:48:21 tb Exp $ */
+/* $OpenBSD: tasn_prn.c,v 1.18 2019/03/23 18:48:14 beck Exp $ */
 /* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
  * project 2000.
  */
@@ -507,7 +507,12 @@ asn1_primitive_print(BIO *out, ASN1_VALUE **fld, const ASN1_ITEM *it,
                 return 0;
         if (pf && pf->prim_print)
                 return pf->prim_print(out, fld, it, indent, pctx);
+
         str = (ASN1_STRING *)*fld;
+
+        if (str->length < 0)
+                return 0;
+
         if (it->itype == ASN1_ITYPE_MSTRING)
                 utype = str->type & ~V_ASN1_NEG;
         else
@@ -516,7 +521,6 @@ asn1_primitive_print(BIO *out, ASN1_VALUE **fld, const ASN1_ITEM *it,
                 ASN1_TYPE *atype = (ASN1_TYPE *)*fld;
                 utype = atype->type;
                 fld = &atype->value.asn1_value;
-                str = (ASN1_STRING *)*fld;
                 if (pctx->flags & ASN1_PCTX_FLAGS_NO_ANY_TYPE)
                         pname = NULL;
                 else
diff --git a/src/lib/libcrypto/bn/bn_lib.c b/src/lib/libcrypto/bn/bn_lib.c
index 0b79a87413..0025cf52ef 100644
--- a/src/lib/libcrypto/bn/bn_lib.c
+++ b/src/lib/libcrypto/bn/bn_lib.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: bn_lib.c,v 1.45 2018/07/23 18:14:32 tb Exp $ */
+/* $OpenBSD: bn_lib.c,v 1.46 2019/03/23 18:48:15 beck Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -578,6 +578,8 @@ BN_bin2bn(const unsigned char *s, int len, BIGNUM *ret)
         BN_ULONG l;
         BIGNUM *bn = NULL;
 
+        if (len < 0)
+                return (NULL);
         if (ret == NULL)
                 ret = bn = BN_new();
         if (ret == NULL)