iconv_open fails when suid bit is on

[guy keren]

running "strace" on an suid binary - ignores the 'suid' bit. so the test 
with strace is not relevant.


--guy

On 02/13/2012 10:56 AM, Elazar Leibovich wrote:
> In RHEL 5 system, libc-6, I'm seeing the following strange phenomena
>
> $ cat iconv_test.c
> #include <stdio.h>
> #include <errno.h>
> #include <fcntl.h>
> #include <iconv.h>
>
> void iconv_test() {
>    static int nr = 0;
>    iconv_t iconv = iconv_open("MSCP949","UTF-8");
>    //iconv_t iconv = iconv_open("UTF-16","UTF-8");
>    if (iconv == (iconv_t)-1) {
>      puts( "can't initialize iconv");
>    } else {
>      puts( "iconv open success!" );
>    }
>    nr++;
> }
>
> int main(int argc,char **argv) {
>    iconv_test();
>    return 0;
> }
>
> $ gcc iconv_test.c
> $ ./a.out
> iconv open success!
> $ sudo su -
> # chown root:foo a.out
> # chmod 4555 a.out
> # su foo -
> $ ./a.out
> can't initialize iconv
> $ strace ./a.out 2>/dev/null
> iconv open success!
>
>
> iconv_open on UTF-16 to UTF-8 succeeds!
> This phenomena doesn't happen in recent Ubuntu.
>
> I'm not familiar with the inner workings of iconv, but stracing a good
> iconv run reveals it dlopen so files according to the chosen encodings,
> maybe it's related.
>
> 1) I'll be glad for any thoughts or ideas how to debug this issue, other
> than downloading the libc source rpm, compiling it, LD_PRELOAD, and hope
> the problem will be recreated.
>
> 2) If someone can test this on a RHEL-5 machine, and report if it
> happens to him too, it could be helpful.
>
> Thanks,
>
>
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