Segfault from /lib/x86_64-linux-gnu/libcrypto.so.1.0.0

Question

我正在嘗試編寫一個小程序在CBC模式下使用OpenSSL和AES加密某些內容。 這裏是我的代碼：

#include <stdio.h> 
#include <stdlib.h> 
#include <string.h> 
#include <stdint.h> 
#include <openssl/aes.h> 
#include <openssl/rand.h> 

// main entrypoint 
int main(int argc, char **argv) 
{ 

    unsigned char *aes_key = malloc(32*sizeof(unsigned char)); 
     printf("Enter a 32 char key\n"); 
     scanf("%s", aes_key); 
     if ((sizeof(aes_key)/sizeof(aes_key[0])) != 8) { 
      fprintf(stderr,"you didn't write 32 char\n"); 
      return -1; 
     } 


    uint64_t msg = 30849384302932039; 

    /* generate input with a given length */ 
    unsigned char *aes_input = malloc(100*sizeof(unsigned char)); 
    sprintf(aes_input, "%lu", msg); 

    /* init vector */ 
    unsigned char *iv = (unsigned char*)malloc(sizeof(unsigned char) *AES_BLOCK_SIZE); 
    RAND_bytes(iv, AES_BLOCK_SIZE); 

    // buffers for encryption and decryption 
    unsigned char *enc_out = malloc(sizeof(unsigned char)*16); 
    sprintf(enc_out, "%d", 0); 

    AES_KEY enc_key, dec_key; 
    AES_set_encrypt_key(aes_key, 32, &enc_key); 
    AES_cbc_encrypt(aes_input, enc_out, 16, &enc_key, iv, AES_ENCRYPT); 

    printf("original:\t + %s\n",aes_input); 
    printf("encrypt:\t + %s\n",enc_out); 

    return 0; 
} 

我編譯它與gcc -g test.c -lcrypto -o test但是當我運行它，我得到一個分段錯誤和gdb指示我：

Program received signal SIGSEGV, Segmentation fault. 
0x00007ffff7a7b9a0 in ??() from /lib/x86_64-linux-gnu/libcrypto.so.1.0.0 

嘗試調試之後，我發現，該行AES_cbc_encrypt(aes_input, enc_out, 15, &enc_key, iv, AES_ENCRYPT);負責segfaut ...但是，所有參數似乎初始化，我試圖打印他們的價值觀，我沒有得到任何問題？

所以我不真的搞錯我做錯了，有人可以幫我嗎？非常感謝你:)

Answer 1

unsigned char *aes_key = malloc(32*sizeof(unsigned char)); 
... 
if ((sizeof(aes_key)/sizeof(aes_key[0])) != 8) { 

這是沒有得到陣列（32）的大小，而是一個指針的大小unsigned char。

同爲

const uint64_t encslength = ((sizeof(aes_input)/sizeof(aes_input[0]) + AES_BLOCK_SIZE)/AES_BLOCK_SIZE) * AES_BLOCK_SIZE; 

看看到Question 7.28 of C FAQ