1

在我的程序上运行 Valgrind 会生成大小为 4 的无效读取错误。我试图找到它，但似乎找不到它。

#define _GNU_SOURCE
#include <stdio.h>
#include <netdb.h>
#include <stdlib.h>
#include <string.h>
#include <libgen.h>
#include <sys/types.h>
#include <sys/socket.h>

void download_file (void){
    int ret;
    char *service = "http";
    char *site = "www.sony.com";
    char *page = "/";
    char *msg;
    struct addrinfo *res;
    struct addrinfo hints;
    const char * format = "GET %s HTTP/1.1\r\nHost: %s\r\nUser-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:30.0) Gecko/20100101 Firefox/30.0\r\n\r\n";
    memset(&hints, 0, sizeof hints);
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_flags = AI_PASSIVE;

    asprintf(&msg, format, page, site);

    if((ret = getaddrinfo(site, service, &hints, &res)) != 0){
        fprintf(stderr, "download_file: getaddrinfo error: %s\n", gai_strerror(ret));
        freeaddrinfo(res);
        free(msg);
        return;
    }
    freeaddrinfo(res);
    free(msg);
    return;
}
int main (void){
    download_file();
    exit(0);
}

这是 Valgrind 的输出：

==3215== Memcheck, a memory error detector
==3215== Copyright (C) 2002-2011, and GNU GPL'd, by Julian Seward et al.
==3215== Using Valgrind-3.7.0 and LibVEX; rerun with -h for copyright info
==3215== Command: ./a.out
==3215== 
==3215== Invalid read of size 4
==3215==    at 0x401718C: strlen (strlen.S:53)
==3215==    by 0x4012F1F: _dl_open (dl-open.c:672)
==3215==    by 0x495982F: do_dlopen (dl-libc.c:86)
==3215==    by 0x400F0BF: _dl_catch_error (dl-error.c:178)
==3215==    by 0x4959917: dlerror_run (dl-libc.c:47)
==3215==    by 0x495997F: __libc_dlopen_mode (dl-libc.c:160)
==3215==    by 0x4935447: __nss_lookup_function (nsswitch.c:434)
==3215==    by 0x493569B: __nss_lookup (nsswitch.c:229)
==3215==    by 0x493DB93: getservbyname_r@@GLIBC_2.4 (getXXbyYY_r.c:203)
==3215==    by 0x48FDBA3: gaih_inet_serv (getaddrinfo.c:164)
==3215==    by 0x48FE917: gaih_inet (getaddrinfo.c:332)
==3215==    by 0x490145F: getaddrinfo (getaddrinfo.c:2438)
==3215==  Address 0x4988e64 is 44 bytes inside a block of size 46 alloc'd
==3215==    at 0x4835978: malloc (vg_replace_malloc.c:263)
==3215==    by 0x400EE03: _dl_signal_error (dl-error.c:90)
==3215==    by 0x400903F: _dl_map_object (dl-load.c:2556)
==3215==    by 0x4013157: dl_open_worker (dl-open.c:226)
==3215==    by 0x400F0BF: _dl_catch_error (dl-error.c:178)
==3215==    by 0x4012C9B: _dl_open (dl-open.c:633)
==3215==    by 0x495982F: do_dlopen (dl-libc.c:86)
==3215==    by 0x400F0BF: _dl_catch_error (dl-error.c:178)
==3215==    by 0x4959917: dlerror_run (dl-libc.c:47)
==3215==    by 0x495997F: __libc_dlopen_mode (dl-libc.c:160)
==3215==    by 0x4935447: __nss_lookup_function (nsswitch.c:434)
==3215==    by 0x493569B: __nss_lookup (nsswitch.c:229)
==3215== 
==3215== 
==3215== HEAP SUMMARY:
==3215==     in use at exit: 0 bytes in 0 blocks
==3215==   total heap usage: 67 allocs, 67 frees, 6,461 bytes allocated
==3215== 
==3215== All heap blocks were freed -- no leaks are possible
==3215== 
==3215== For counts of detected and suppressed errors, rerun with: -v
==3215== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 25 from 11)

有人可以帮我理解为什么会发生这个错误吗？或者如何纠正？在我的搜索中，我只发现与 gethostbyaddr() 相关的错误。

看起来无效的读取错误来自 getaddrinfo()，但我无法在我的系统上找到文件 getaddrinfo.c 来尝试纠正它。

4

2 回答 2

1

这看起来像一个类似于这里讨论的问题：http: //git.661346.n2.nabble.com/PATCH-valgrind-ignore-SSE-based-strlen-invalid-reads-td6175816.html

strlen()在搜索空终止符字符时，优化的通常会读取完整的单词。这可以通过实现以安全的方式完成，即使它在技术上违反了分配边界。

可能是您需要更新版本的 valgrind（当前为 3.9.0），或者需要为您正在使用的运行时配置或修补 valgrind。您可能需要为此配置抑制：http: //valgrind.org/docs/manual/manual-core.html#manual-core.suppress

于 2014-08-10T03:53:22.623 回答
0

看起来像是 GNU libc 的问题。查看 valgrind 输出，我猜您使用的是相当旧的 GNU libc 版本？

Valgrind 输出中显示的文件名和行号并不（总是）对应于文件系统上的真实文件。Valgrind 从由编译器放入可执行二进制文件的调试信息部分中获取文件名和行号。

于 2014-08-09T19:31:30.623 回答