Messages in this thread | | | Date | Sun, 3 Jul 2011 12:15:22 -0700 | From | Kees Cook <> | Subject | Re: [PATCH] x86: add missing verify_cpu to 32bit wakeup |
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Hi Pavel,
On Sun, Jul 03, 2011 at 02:15:49PM +0200, Pavel Machek wrote: > > Some BIOSes will reset the Intel XD_DISABLE MSR bit when resuming from S3, > > which can interact poorly with ebba638ae723d8a8fc2f7abce5ec18b688b791d7. > > In 32bit PAE mode, this can lead to a fault when EFER is restored by > > the kernel wakeup routines, due to it setting the NX bit for a CPU > > that (thanks to the BIOS reset) now incorrectly thinks it lacks the NX > > feature. 64bit wakeup already handled this through its common call path > > that would hit verify_cpu(). 32bit has a separate path for restoring > > CPU state on S3 wakeup, and needed to call verify_cpu() to handle this > > situation. > > > > Signed-off-by: Kees Cook <kees.cook@canonical.com> > > Cc: stable@kernel.org > > Looks ok to me, but I'm not sure it is stable material.
Well, I figured anything that shipped with ebba638ae723d8a8fc2f7abce5ec18b688b791d7 should get it, since it is a regression in the 32bit PAE with BIOS-disabled NX corner-case.
-Kees
-- Kees Cook Ubuntu Security Team
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