segfault in strlen

[arno@renevier.net]

hi, I experience a segfault when using  strlen. First time it happened was
when doing:
strlen(argv[0]), but it also happens when doing strlen(stdup(argv[0])) and in
some other configurations. When a string triggers a segfault, I can printf it
correctly, what's more: I can also traverse the string and detect final '\0' at
its correct place (so, what's wrong with strlen?).

see demo crash below. I'm using libc6 and libc6-dev
versions 2.11.1-2 from unstable, and gcc 4.4.4-4 (also from unstable). Here is
a small code that triggers the segfault with some comments explaining the
issue. All I get in gdb is that segfault happens in strlen, even after
installing libc6-dbg. How can I debug this issue more ?
thanks


// compile with gcc -o test test.c
#include <stdio.h>
#include <string.h>


int
main(int argc, char **argv)
{
    const char *path = argv[0];
    // all those path definitions will result in a crash in strlen
    //const char* path = "path\0";
    //const char* path = "path";
    //const char* path = strdup(argv[0]);

    // prints command name correctly
    printf("command is: %s\n", path);

    int i = 0;
    for (i = 0; i < 1020; i++) {
        if (path[i] == '\0') {
            break;
        }
    }
    // XXX: prints correct string length
    printf("computed length: %d\n", i);

    // crashes:
    // (gdb) where
    // #0  0x0000000000401a00 in strlen ()
    // #1  0x00000000004005dc in main ()
    printf("command length: %d\n", strlen(path));
    return 0;
}