Subject: Re: [PATCH] uts: Don't randomize "struct uts_namespace". To: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>, Ken'ichi Ohmichi <oomichi@xxxxxxxxxxxxxxxxx>, Masaki Tachibana <mas-tachibana@xxxxxxxxxxxxx>, Kazuhito Hagio <k-hagio@xxxxxxxxxxxxx> Cc: Kees Cook <keescook@xxxxxxxxxxxx>, Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx> From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> Date: Sat, 7 Jul 2018 08:10:08 +0900 Hello Ken'ichi, I noticed that makedumpfile ( https://sourceforge.net/p/makedumpfile/code/ ) can no longer detect kernel version correctly because "struct uts_namespace" (which is exposed to userspace via vmcoreinfo) is subjected to randomization by GCC_PLUGIN_RANDSTRUCT kernel config option since 4.13. The code was introduced by below commit. commit bfc8fe181c822ad0d8495ceda3c7109a407192f0 Author: ken1_ohmichi <ken1_ohmichi> Date: Fri Dec 22 07:41:14 2006 +0000 linux-2.6.19 support. On linux-2.6.18 or former, the release information could be gotten from the symbol "system_utsname". But on linux-2.6.19, it can be done from the symbol "init_uts_ns". A new makedumpfile can get the release information from the existing symbol. Can you detect kernel version without using "struct uts_namespace" ? On 2018/07/07 1:11, Linus Torvalds wrote: > On Fri, Jul 6, 2018 at 3:07 AM Tetsuo Handa > <penguin-kernel@xxxxxxxxxxxxxxxxxxx> wrote: >> >> I noticed that makedumpfile utility is failing to check kernel version, for >> it depends on offset of "struct uts_namespace"->name being sizeof(int). > > For something like this, we fix makedumpfile instead. This is not a > "user program" using system calls etc, this is something that delves > into the kernel dump and tries to make sense of it. > > Where is the makedumpfile source code? What is it trying to do, and why? > > One option is to just say "hey, you can't make much sense of a > randomized kernel dump anyway, so don't even try". > > Linus > _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
