Why would the same binary want linux-vdso.so.1 on one 64-bit RHEL 5.4 server and not another?

Question

I have a customer running a file parsing program called cleanfileg and as of the last update, he is getting date-format error when parsing a file.

What's bizarre is that we're both running the same program, on the same file, with the same builds of gcc, pthread, libc etc. on the same release of RHEL64 (5.4) and I cannot replicate his issue. He can roll back to last month's version of cleanfileg and everything works fine, so I'm pretty sure that a line-by-line through the source will likely find me an answer, but what's confusing to me is that on a whim, I asked him to run ldd on his executable to see if he was pulling in some different verions of the shared objects.

His-

# ldd cleanfileg
linux-vdso.so.1 =>  (0x00002ad4c98d1000)
libmdGeo.so => /tools/clean_address/bin/libmdGeo.so (0x00002ad4c98d6000)
libmdName.so => /tools/clean_address/bin/libmdName.so (0x00002ad4c9a70000)
libmdPhone.so => /tools/clean_address/bin/libmdPhone.so (0x00002ad4c9df1000)
libmdAddr.so => /tools/clean_address/bin/libmdAddr.so (0x00002ad4ca28c000)
libresolv.so.2 => /lib64/libresolv.so.2 (0x0000003833600000)
libAddressDoctor5.so => /tools/clean_address/bin/libAddressDoctor5.so (0x00002ad4ca96d000)
libstdc++.so.6 => /usr/lib64/libstdc++.so.6 (0x0000003831600000)
libm.so.6 => /lib64/libm.so.6 (0x000000382b200000)
libgcc_s.so.1 => /lib64/libgcc_s.so.1 (0x0000003830a00000)
libpthread.so.0 => /lib64/libpthread.so.0 (0x000000382ba00000)
libc.so.6 => /lib64/libc.so.6 (0x000000382ae00000)
librt.so.1 => /lib64/librt.so.1 (0x000000382d200000)
/lib64/ld-linux-x86-64.so.2 (0x000000382aa00000)

-Mine

#ldd cleanfileg
libmdGeo.so (0x00002ab5d3342000)
libmdName.so (0x00002ab5d34cf000)
libmdPhone.so (0x00002ab5d3850000)
libmdAddr.so (0x00002ab5d3ceb000)
libresolv.so.2 => /lib64/libresolv.so.2 (0x00000034bde00000)
libAddressDoctor5.so (0x00002ab5d43bf000)
libstdc++.so.6 => /usr/lib64/libstdc++.so.6 (0x00000034c9000000)
libm.so.6 => /lib64/libm.so.6 (0x00000034b6200000)
libgcc_s.so.1 => /lib64/libgcc_s.so.1 (0x00000034c7c00000)
libpthread.so.0 => /lib64/libpthread.so.0 (0x00000034b6a00000)
libc.so.6 => /lib64/libc.so.6 (0x00000034b5e00000)
librt.so.1 => /lib64/librt.so.1 (0x00000034b6e00000)
/lib64/ld-linux-x86-64.so.2 (0x00000034b5a00000)

Is linux-vdso.so.1 something that is needed (or not) as dictated by configuration somehow? How/why would it be required by what other wise seem to be identical machines running identical code?

Any next steps anyone could suggest for debugging?

Answer 1

Is linux-vdso.so.1 something that is needed (or not) as dictated by configuration somehow?

The linux-vdso.so.1 is a "library" that is injected into every process by the kernel. Read more about it here.

You likely have different kernel versions, which would explain why you are seeing different ldd output.