On Wed, Mar 22, 2017 at 5:50 AM, Evgenii Shatokhin <[email protected]> wrote: > On 21.03.2017 23:40, Kees Cook wrote: >> >> On Tue, Mar 21, 2017 at 6:54 AM, Evgenii Shatokhin >> <[email protected]> wrote: >>> >>> Hi, >>> >>> One of my x86 machines with a 32-bit Linux system (ROSA Linux in this >>> case) >>> automatically reboots when it tries to resume from hibernate. This >>> happens >>> shortly after "Image loading progress 100%" message is shown on the >>> screen. >>> >>> No traces of the error are in the system log after reboot though. >>> >>> The problem is present at least in the mainline kernels 4.8 - 4.10. With >>> earlier versions (I tried 4.4, 4.5, etc.), the system resumes OK. >>> >>> The bisection pointed to the following commit as the first "bad" one: >>> >>> commit 65fe935dd2387a4faf15314c73f5e6d31ef0217e >>> Author: Kees Cook <[email protected]> >>> Date: Mon Jun 13 15:10:02 2016 -0700 >>> >>> x86/KASLR, x86/power: Remove x86 hibernation restrictions >> >> >> Hrm, perhaps the 32-bit hibernation code still isn't KASLR-safe. If >> you boot with nokaslr on the kernel command line, does the problem go >> away? > > > Yes. The problem does not show up when I boot the system with 'nokaslr'.
Okay, it looks like we need to either partially revert that commit (i.e. make the by-default-prefer-hibernation logic only happen on 32-bit x86), swap the logic (i.e. by-default-prefer-KASLR on 32-bit), or make KASLR be blocked by hibernation in Kconfig (as it was a long time ago). Rafael, do you have a preference here? -Kees -- Kees Cook Pixel Security
