Suggested Patch is not working for 22851 Bugzilla issue

From: Bala S
Date: Tue Nov 19 2019 - 00:07:56 EST


Hi Mhocko,

https://sourceware.org/bugzilla/show_bug.cgi?id=22851
For the above issue, I have found the patch.

Patch link:
https://www.mail-archive.com/linux-kernel@xxxxxxxxxxxxxxx/msg1561935.html

Only change i noticed is 'MAP_FIXED_NOREPLACE' is used instead of
'MAP_FIXED_SAFE'.

I ran test case on the following targets with this patch:

1. For X86-64, Still i could see the reported issue( 'libevil.so' just
runs âcat /etc/passwd')

2. For MIPS-64, i am not seeing the malicious file content as
reported. But âlddâ could not found âlibevil.soâ.

root@qemumips64:~/LIN1019-1806# ldd ./main
linux-vdso.so.1 (0x000000fff1f20000)
libevil.so => not found
libc.so.6 => /lib/libc.so.6 (0x0000005e46f70000)
/lib/ld.so.1 (0x000000fff7888000)

I am not clear why this patch is not working for X86-64? But it is
working for MIPS-64 with some issue.
Please let me know, if anything is pending on this patch for the reported issue.

Thanks,
Bala