x86/fault: Improve kernel-executing-user-memory handling

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Right now, the case of the kernel trying to execute from user memory
is treated more or less just like the kernel getting a page fault on a
user access. In the failure path, it checks for erratum #93, tries to
otherwise fix up the error, and then oopses.

If it manages to jump to the user address space, with or without SMEP,
it should not try to resolve the page fault. This is an error, pure and
simple. Rearrange the code so that this case is caught early, check for
erratum #93, and bail out.

 [ bp: Massage commit message. ]

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/ab8719c7afb8bd501c4eee0e36493150fbbe5f6a.1612924255.git.luto@kernel.org

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Andy Lutomirski 2021-02-09 18:33:39 -08:00 • committed by Borislav Petkov

parent 56e62cd28a

commit 03c81ea333

1 changed files with 18 additions and 3 deletions

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arch/x86/mm/fault.c

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