On Wed, Nov 3, 2010 at 8:33 AM, Alexey Suslikov
<alexey.suslikov@gmail.com> wrote:
quoted text
> This is somewhat ports related, but I decided to ask here before going
> further with diff.
>
> Well, we have Asterisk 1.6.2.14-rc1 going segfault:
>
> #0  generic_http_callback (format=FORMAT_XML, remote_address=0x4001,
>    uri=0x4001 <Address 0x4001 out of bounds>, method=205216842,
>    params=0x20eb5bc00, status=0x2057b2c74, title=0x2057b2c78,
>    contentlength=0x2057b2c84) at manager.c:4005
> 4005
>
> #0  generic_http_callback (format=FORMAT_XML, remote_address=0x4001,
>    uri=0x4001 <Address 0x4001 out of bounds>, method=205216842,
>    params=0x20eb5bc00, status=0x2057b2c74, title=0x2057b2c78,
>    contentlength=0x2057b2c84) at manager.c:4005
>        buf = 0x208dd5000 <Address 0x208dd5000 out of bounds>
>        l = 16384
>        s = {session = 0x203382800, f = 0x2036d3440, fd = 245}
>        session = (struct mansession_session *) 0x203382800
>        ident = 390437576
>        blastaway = 0
>        v = (struct ast_variable *) 0x4000
>        template = "/tmp/ast-http-U9afaz"
>        out = (struct ast_str *) 0x207fd7800
>        m = {hdrcount = 2, headers = {0x2057b2470 "Action:
CoreShowChannels",
quoted text
>    0x2057b2450 "mansession_id: 17459ac8", 0x0 <repeats 126 times>}}
>        x = 16385
>        hdrlen = 0
>
> Relevant lines are:
>
>        if (s.f != NULL) {      /* have temporary output */
>                char *buf;
>                size_t l;
>
>                if ((l = ftell(s.f))) {
>                        if (MAP_FAILED == (buf = mmap(NULL, l + 1,
> PROT_READ | PROT_WRITE, MAP_PRIVATE, s.fd, 0))) {
>                                ast_log(LOG_WARNING, "mmap failed.
> Manager output was not processed\n");
>                        } else {
> =>4005:                    buf[l] = '__PLACEHOLDER__1_';
>                                if (format == FORMAT_XML || format ==
> FORMAT_HTML) {
>                                        xml_translate(&out, buf,
> params, format);
>                                } else {
>                                        ast_str_append(&out, 0, "%s", buf);
>                                }
>                                munmap(buf, l + 1);
>                        }
>                } else if (format == FORMAT_XML || format == FORMAT_HTML) {
>                        xml_translate(&out, "", params, format);
>                }
>                fclose(s.f);
>                s.f = NULL;
>                s.fd = -1;
>        }
>
> So if ftell() returns value of l exactly at the end of file, accessing
> l + 1 leads to segfault while mmaping l + 1 is ok, right?

mmapping l + 1 doesn't really make sense, you can only map the bytes
that are in the file.  the call succeeds, but you aren't going to grow
the file or get more memory.  if you want a null terminated string,
either null terminate the file or copy it to a buffer in memory.