Commit 6ac9fda4 authored by David Benjamin's avatar David Benjamin Committed by Richard Levitte
Browse files

Pretty-print large INTEGERs and ENUMERATEDs in hex. 



This avoids taking quadratic time to pretty-print certificates with
excessively large integer fields. Very large integers aren't any more
readable in decimal than hexadecimal anyway, and the i2s_* functions
will parse either form.

Found by libFuzzer.

Reviewed-by: default avatarRich Salz <rsalz@openssl.org>
Reviewed-by: default avatarRichard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4790)

(cherry picked from commit 10a3195f)
parent 5d612d37

crypto/x509v3/v3_utl.c

+40 −2
Original line number Diff line number Diff line
@@ -13,6 +13,7 @@ 
#include <ctype.h>

#include "internal/cryptlib.h"

#include <openssl/conf.h>

#include <openssl/crypto.h>

#include <openssl/x509v3.h>

#include "internal/x509_int.h"

#include <openssl/bn.h>
@@ -99,6 +100,43 @@ int X509V3_add_value_bool_nf(const char *name, int asn1_bool, 
    return 1;

}



static char *bignum_to_string(const BIGNUM *bn)

{

    char *tmp, *ret;

    size_t len;



    /*

     * Display large numbers in hex and small numbers in decimal. Converting to

     * decimal takes quadratic time and is no more useful than hex for large

     * numbers.

     */

    if (BN_num_bits(bn) < 128)

        return BN_bn2dec(bn);



    tmp = BN_bn2hex(bn);

    if (tmp == NULL)

        return NULL;



    len = strlen(tmp) + 3;

    ret = OPENSSL_malloc(len);

    if (ret == NULL) {

        X509V3err(X509V3_F_BIGNUM_TO_STRING, ERR_R_MALLOC_FAILURE);

        OPENSSL_free(tmp);

        return NULL;

    }



    /* Prepend "0x", but place it after the "-" if negative. */

    if (tmp[0] == '-') {

        OPENSSL_strlcpy(ret, "-0x", len);

        OPENSSL_strlcat(ret, tmp + 1, len);

    } else {

        OPENSSL_strlcpy(ret, "0x", len);

        OPENSSL_strlcat(ret, tmp, len);

    }

    OPENSSL_free(tmp);

    return ret;

}



char *i2s_ASN1_ENUMERATED(X509V3_EXT_METHOD *method, const ASN1_ENUMERATED *a)

{

    BIGNUM *bntmp = NULL;
@@ -107,7 +145,7 @@ char *i2s_ASN1_ENUMERATED(X509V3_EXT_METHOD *method, const ASN1_ENUMERATED *a) 
    if (!a)

        return NULL;

    if ((bntmp = ASN1_ENUMERATED_to_BN(a, NULL)) == NULL

        || (strtmp = BN_bn2dec(bntmp)) == NULL)

        || (strtmp = bignum_to_string(bntmp)) == NULL)

        X509V3err(X509V3_F_I2S_ASN1_ENUMERATED, ERR_R_MALLOC_FAILURE);

    BN_free(bntmp);

    return strtmp;
@@ -121,7 +159,7 @@ char *i2s_ASN1_INTEGER(X509V3_EXT_METHOD *method, const ASN1_INTEGER *a) 
    if (!a)

        return NULL;

    if ((bntmp = ASN1_INTEGER_to_BN(a, NULL)) == NULL

        || (strtmp = BN_bn2dec(bntmp)) == NULL)

        || (strtmp = bignum_to_string(bntmp)) == NULL)

        X509V3err(X509V3_F_I2S_ASN1_INTEGER, ERR_R_MALLOC_FAILURE);

    BN_free(bntmp);

    return strtmp;

crypto/x509v3/v3err.c

+2 −1
Original line number Diff line number Diff line 
/*

 * Generated by util/mkerr.pl DO NOT EDIT

 * Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.

 * Copyright 1995-2017 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the OpenSSL license (the "License").  You may not use

 * this file except in compliance with the License.  You can obtain a copy
@@ -26,6 +26,7 @@ static ERR_STRING_DATA X509V3_str_functs[] = { 
     "ASIdentifierChoice_canonize"},

    {ERR_FUNC(X509V3_F_ASIDENTIFIERCHOICE_IS_CANONICAL),

     "ASIdentifierChoice_is_canonical"},

    {ERR_FUNC(X509V3_F_BIGNUM_TO_STRING), "bignum_to_string"},

    {ERR_FUNC(X509V3_F_COPY_EMAIL), "copy_email"},

    {ERR_FUNC(X509V3_F_COPY_ISSUER), "copy_issuer"},

    {ERR_FUNC(X509V3_F_DO_DIRNAME), "do_dirname"},

include/openssl/x509v3.h

+1 −0
Original line number Diff line number Diff line
@@ -876,6 +876,7 @@ int ERR_load_X509V3_strings(void); 
# define X509V3_F_ADDR_VALIDATE_PATH_INTERNAL             166

# define X509V3_F_ASIDENTIFIERCHOICE_CANONIZE             161

# define X509V3_F_ASIDENTIFIERCHOICE_IS_CANONICAL         162

# define X509V3_F_BIGNUM_TO_STRING                        167

# define X509V3_F_COPY_EMAIL                              122

# define X509V3_F_COPY_ISSUER                             123

# define X509V3_F_DO_DIRNAME                              144