在OS X中从main返回时出现中止陷阱6,但在linux中没有

Abort trap 6 when returning from main in OS X but NOT on linux

本文关键字:陷阱 但在 linux 中从 OS main 返回      更新时间:2023-10-16

我有一个程序,目前似乎在Linux (Ubuntu 14.04)上运行良好,但在OS X(10.11.6)上运行时,我得到一个中止陷阱6。我已经附上了我的代码,但我怀疑这个问题实际上并不与特定的代码有关。这段代码是为了一个课程项目,我并不是想要破解密码或其他东西。

下面是代码,我相信所有重要的东西都发生在main中。
#include <openssl/aes.h>   
#include <openssl/evp.h>
#include <openssl/conf.h>
#include <openssl/err.h>

#define KEY_BYTES KEY_LENGTH/8
#define KEY_LENGTH 128

unsigned char*  h(unsigned char* p, unsigned char* hp);
void handleErrors(void);
int encrypt(unsigned char *plaintext, int plaintext_len, unsigned char *key,
            unsigned char *iv, unsigned char *ciphertext);

//assumes we've already padded with zeros
unsigned char*  h(unsigned char* p, unsigned char *hp){
    encrypt((unsigned char*)"0000000000000000", KEY_BYTES, p , (unsigned char*)"0000000000000000", hp);
    return hp; 
}
void handleErrors(void)
{
    printf("panic!!n");
    //ERR_print_errors_fp(stderr); //sg: throw a real error you fool!
    abort();
}
//sg: stolen from the evp man page
int encrypt(unsigned char *plaintext, int plaintext_len, unsigned char *key,
            unsigned char *iv, unsigned char *ciphertext)
{
    EVP_CIPHER_CTX *ctx;
    int len;
    int ciphertext_len;
    /* Create and initialise the context */
    if(!(ctx = EVP_CIPHER_CTX_new())) handleErrors();
    /* Initialise the encryption operation. IMPORTANT - ensure you use a key
     * and IV size appropriate for your cipher
     * In this example we are using 256 bit AES (i.e. a 256 bit key). The
     * IV size for *most* modes is the same as the block size. For AES this
     * is 128 bits */
    if(1 != EVP_EncryptInit_ex(ctx, EVP_aes_128_cbc(), NULL, key, iv))
        handleErrors();
    /* Provide the message to be encrypted, and obtain the encrypted output.
     * EVP_EncryptUpdate can be called multiple times if necessary
     */
    if(1 != EVP_EncryptUpdate(ctx, ciphertext, &len, plaintext, plaintext_len))
        handleErrors();
    ciphertext_len = len;
    /* Finalise the encryption. Further ciphertext bytes may be written at
     * this stage.
     */
    if(1 != EVP_EncryptFinal_ex(ctx, ciphertext + len, &len)) handleErrors();
    ciphertext_len += len;
    /* Clean up */
    EVP_CIPHER_CTX_free(ctx);
    return ciphertext_len;
}

int main(){
    /* Initialise the library */
    ERR_load_crypto_strings();
    OpenSSL_add_all_algorithms();
    OPENSSL_config(NULL);
    EVP_CIPHER_CTX *ctx;
    unsigned char hp[KEY_BYTES];
    /* Create and initialise the context */
    if(!(ctx = EVP_CIPHER_CTX_new())) handleErrors();
    h((unsigned char*) "1111111111111111", hp);
    for(int i = 0; i < KEY_BYTES; i++){
        printf("h(%i) = %xn", i, hp[i]);
    }
    return 0;
}

当在linux上运行时,我得到以下(这是我所期望的)

h(0) = 10
h(1) = df
h(2) = c1
h(3) = b5
h(4) = f6
h(5) = 6c
h(6) = fd
h(7) = 6a
h(8) = 1d
h(9) = c4
h(10) = 6d
h(11) = 66
h(12) = 90
h(13) = 7b
h(14) = ee
h(15) = b1

然而,当我在OS X上运行时,我得到以下内容:

h(0) = 10
h(1) = df
h(2) = c1
h(3) = b5
h(4) = f6
h(5) = 6c
h(6) = fd
h(7) = 6a
h(8) = 1d
h(9) = c4
h(10) = 6d
h(11) = 66
h(12) = 90
h(13) = 7b
h(14) = ee
h(15) = b1
Abort trap: 6

当我将它弹出到gdb中时,我得到以下

(gdb) r
Starting program: /Users/sgillen/Code/457/proj3/a.out 
h(0) = 10
h(1) = df
h(2) = c1
h(3) = b5
h(4) = f6
h(5) = 6c
h(6) = fd
h(7) = 6a
h(8) = 1d
h(9) = c4
h(10) = 6d
h(11) = 66
h(12) = 90
h(13) = 7b
h(14) = ee
h(15) = b1
Program received signal SIGABRT, Aborted.
0x00007fff93150f06 in __pthread_kill () from /usr/lib/system/libsystem_kernel.dylib
(gdb) where
#0  0x00007fff93150f06 in __pthread_kill () from /usr/lib/system/libsystem_kernel.dylib
#1  0x00007fff97b374ec in pthread_kill () from /usr/lib/system/libsystem_pthread.dylib
#2  0x00007fff9ba8077f in __abort () from /usr/lib/system/libsystem_c.dylib
#3  0x00007fff9ba8105e in __stack_chk_fail () from /usr/lib/system/libsystem_c.dylib
#4  0x0000000100000ea9 in main () at gen_table.cpp:90

不确定如何在堆栈溢出时做行号,但gen_table.cpp的第90行是main中最后返回0的行号。

如果相关的话,我用下面的代码编译我的代码。

clang -Wall -std=c++11 gen_table.cpp  -I/usr/local/opt/openssl/include/ -lcrypto -lssl -g

任何帮助都将非常感激,谢谢!

我找到了我的问题的答案,我想我会为任何遇到同样问题的人发布答案。问题是我重写了自己的堆栈。我使用的加密函数实际上是向hp写入32字节(这是堆栈上的16字节无符号字符)。所以我会销毁我自己的堆栈,但不会写入任何不属于我的进程的内存。这导致没有segfault,但当程序试图返回时,最终出现了问题。杀死我的确切原因取决于我如何编译我的代码。

我真的很惊讶valgrind没有发现这个。我仍然不知道为什么当用clang编译时,它似乎在linux上工作得很好(用g++编译时,我得到了一个堆栈粉碎检测到的错误)。

编辑:明确地说,解决方案是修复我的encrypt实现,使其只写入16字节。我只是通过注释EVP_EncryptFinal_ex调用来做到这一点。

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