Commit 3a9b9b2d authored by Kurt Roeckx's avatar Kurt Roeckx
Browse files

Make the random number generator predictable when fuzzing. 



Reviewed-by: default avatarRich Salz <rsalz@openssl.org>
GH: #2023
parent 3a85d05f

crypto/rand/md_rand.c

+2 −2
Original line number Diff line number Diff line
@@ -33,7 +33,7 @@ 
# include <openssl/fips.h>

#endif



#ifdef BN_DEBUG

#if defined(BN_DEBUG) || defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION)

# define PREDICT

#endif
@@ -307,7 +307,7 @@ static int rand_bytes(unsigned char *buf, int num, int pseudo) 


#ifdef PREDICT

    if (rand_predictable) {

        static unsigned char val = 0;

        unsigned char val = 0;



        for (i = 0; i < num; i++)

            buf[i] = val++;

fuzz/README.md

+2 −1
Original line number Diff line number Diff line
@@ -38,7 +38,8 @@ Configure for fuzzing: 
    $ CC=clang ./config enable-fuzz-libfuzzer \

            --with-fuzzer-include=../../svn-work/Fuzzer \

            --with-fuzzer-lib=../../svn-work/Fuzzer/libFuzzer \

            -DPEDANTIC enable-asan enable-ubsan no-shared

            -DPEDANTIC enable-asan enable-ubsan no-shared \

            -DFUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION

    $ sudo apt-get install make

    $ LDCMD=clang++ make -j

    $ fuzz/helper.py $FUZZER

fuzz/server.c

+8 −0
Original line number Diff line number Diff line
@@ -191,6 +191,10 @@ static const uint8_t kRSAPrivateKeyDER[] = { 


static SSL_CTX *ctx;



#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION

extern int rand_predictable;

#endif



int FuzzerInitialize(int *argc, char ***argv)

{

    const uint8_t *bufp = kRSAPrivateKeyDER;
@@ -214,6 +218,10 @@ int FuzzerInitialize(int *argc, char ***argv) 
    OPENSSL_assert(ret == 1);

    X509_free(cert);



#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION

    rand_predictable = 1;

#endif



    return 1;

}