On Mon, Feb 13, 2012 at 11:45:26AM +0200, guy keren wrote: > > running "strace" on an suid binary - ignores the 'suid' bit. so the > test with strace is not relevant.
Indeed, and to strace programs that do this, I do something like that: Open a root shell: # echo $$ let's say it printed 1234, so its pid is 1234 Open another root shell: # strace -f -o /tmp/trace1 -p 1234 Now, inside 1234 run what you need to debug. 'strace -f -p pid' does follow correctly the uid changes caused by suid binaries and setuid etc. Some years ago I played a bit with the more obvious # strace -f su - user -c program which then did not work well. Not sure if this was changed. '-f -p pid' always worked for me. Sorry I can't comment about the actual OP quesion, but just a guess - perhaps it's on nfs? -- Didi > 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, > > > > > >_______________________________________________ > >Linux-il mailing list > >Linux-il@cs.huji.ac.il > >http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il > > > _______________________________________________ > Linux-il mailing list > Linux-il@cs.huji.ac.il > http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il _______________________________________________ Linux-il mailing list Linux-il@cs.huji.ac.il http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il