Re: MD5SUMs differ across cluster nodes: Any ideas?
Junhao <[email protected]>
| Newsgroups | gmane.user-groups.linux.singapore |
|---|---|
| Message-ID | <[email protected]> |
On 04/09/2010 10:11 AM, Michael Clark wrote: > Hi Junhao, > > On Friday 09,April,2010 09:53 AM, Junhao wrote: >> A couple of us dug further. It seems that dynamically linked binaries >> have different md5sums, while static binaries have the same. Still not >> quite sure why though... >> >> Regards, >> Junhao > > If the systems had prelinking (popular in fedora a few years ago), all > of the the shared objects get rewritten with non-conflicting link > addresses (to avoid runtime relocation overhead). It is usually set up > in /etc/cron (check cron.daily, cron.weekly, etc) > > I'm not sure if more recent linux systems use prelinking or not - it may > conflict with link address randomisation (a security mechanism, so that > exploits can't run code that targets known address offsets). e.g. look > at the link addresses of /bin/ls over two runs (on Debian Sid/2.6.32): > > mclark@monty:~$ ldd /bin/ls > libselinux.so.1 => /lib/libselinux.so.1 (0xb777f000) > librt.so.1 => /lib/i686/cmov/librt.so.1 (0xb7776000) > libacl.so.1 => /lib/libacl.so.1 (0xb776e000) > libc.so.6 => /lib/i686/cmov/libc.so.6 (0xb7627000) > libdl.so.2 => /lib/i686/cmov/libdl.so.2 (0xb7623000) > /lib/ld-linux.so.2 (0xb77b6000) > libpthread.so.0 => /lib/i686/cmov/libpthread.so.0 (0xb760a000) > libattr.so.1 => /lib/libattr.so.1 (0xb7605000) > mclark@monty:~$ ldd /bin/ls > libselinux.so.1 => /lib/libselinux.so.1 (0xb788a000) > librt.so.1 => /lib/i686/cmov/librt.so.1 (0xb7881000) > libacl.so.1 => /lib/libacl.so.1 (0xb7879000) > libc.so.6 => /lib/i686/cmov/libc.so.6 (0xb7732000) > libdl.so.2 => /lib/i686/cmov/libdl.so.2 (0xb772e000) > /lib/ld-linux.so.2 (0xb78c1000) > libpthread.so.0 => /lib/i686/cmov/libpthread.so.0 (0xb7715000) > libattr.so.1 => /lib/libattr.so.1 (0xb7710000) > Ahh.... That might explain it. Will check when I get back to office next week. FYI, we are testing on Redhat Enterprise Linux 5.x. -- Regards, Junhao _______________________________________________ LUGS Mailing list - [email protected] List FAQ: http://wiki.lugs.org.sg/LugsMailingListFaq Info page: http://www.lugs.org.sg/mailman/listinfo/slugnet To unsubscribe send an empty email to: [email protected]