lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Tue, 2 Jun 2020 11:27:08 -0600 From: Shuah Khan <skhan@...uxfoundation.org> To: Andy Lutomirski <luto@...nel.org>, Borislav Petkov <bp@...en8.de>, Shuah Khan <shuah@...nel.org> Cc: Petteri Aimonen <jpa@....mail.kapsi.fi>, Dave Hansen <dave.hansen@...el.com>, "H. Peter Anvin" <hpa@...or.com>, x86-ml <x86@...nel.org>, lkml <linux-kernel@...r.kernel.org>, skhan@...uxfoundation.org Subject: Re: [PATCH] arch/x86: reset MXCSR to default in kernel_fpu_begin() On 6/2/20 11:03 AM, Andy Lutomirski wrote: > On Tue, Jun 2, 2020 at 3:56 AM Borislav Petkov <bp@...en8.de> wrote: >> >> Hi, >> >> On Tue, Jun 02, 2020 at 01:29:51PM +0300, Petteri Aimonen wrote: >>> The kernel module is not actually x86-specific, even though it is >>> currently only enabled for x86. amdgpu driver already does kernel mode >>> floating point operations on PPC64 also, and the same module could be >>> used to test the same thing there. >> >> Then make it generic please and put the user portion in, say, >> tools/testing/selftests/fpu/ and we can ask ppc people to test it too. >> People might wanna add more stuff to it in the future, which would be >> good. >> >>> To deterministically trigger the bug, the syscall has to come from the >>> same thread that has modified MXCSR. Going through /usr/sbin/modprobe >>> won't work, and manually doing the necessary syscalls for module loading >>> seems too complicated. >> >> Ok, fair enough. But put that file in debugfs pls. > > I think I agree. While it would be delightful to have general > selftest tooling for kernel modules, we don't have that right now, and > having the test just work with an appropriately configured kernel > would be nice. > Let's extend it to do what we want it to do. I will happy to take patches. If you have some concrete ideas on what we can add, please do a short summary of what is missing. I will find a way to get this done. > How about putting the file you frob in > /sys/kernel/debug/selftest_helpers/something_or_other. The idea would > be that /sys/kernel/debug/selftest_helpers would be a general place > for kernel helpers needed to make selftests work. > Is this a workaround for the lack of selftest tooling for kernel modules? In which case, let's us focus on fix selftest tooling. thanks, -- Shuah
Powered by blists - more mailing lists