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| H A D | fault.c | diff 56e62cd28aaae2fcbec8af67b05843c47c6da170 Tue Feb 09 20:33:38 CST 2021 Andy Lutomirski <luto@kernel.org> x86/fault: Correct a few user vs kernel checks wrt WRUSS
In general, page fault errors for WRUSS should be just like get_user(),
etc. Fix three bugs in this area:
There is a comment that says that, if the kernel can't handle a page fault
on a user address due to OOM, the OOM-kill-and-retry logic would be
skipped. The code checked kernel *privilege*, not kernel mode, so it
missed WRUSS. This means that the kernel would malfunction if it got OOM
on a WRUSS fault -- this would be a kernel-mode, user-privilege fault, and
the OOM killer would be invoked and the handler would retry the faulting
instruction.
A failed user access from kernel while a fatal signal is pending should
fail even if the instruction in question was WRUSS.
do_sigbus() should not send SIGBUS for WRUSS -- it should handle it like
any other kernel mode failure.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/a7b7bcea730bd4069e6b7e629236bb2cf526c2fb.1612924255.git.luto@kernel.org
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