Commit ebb53e25 authored Nov 21, 2018 by Andy Lutomirski Committed by Ingo Molnar Nov 22, 2018

x86/fault: Don't try to recover from an implicit supervisor access

This avoids a situation in which we attempt to apply various fixups
that are not intended to handle implicit supervisor accesses from
user mode if we screw up in a way that causes this type of fault.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Link: http://lkml.kernel.org/r/9999f151d72ff352265f3274c5ab3a4105090f49.1542841400.git.luto@kernel.org

Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 0ed32f1a

arch/x86/mm/fault.c

+10 −0

Original line number	Diff line number	Diff line
		@@ -653,6 +653,15 @@ no_context(struct pt_regs *regs, unsigned long error_code,
		unsigned long flags;
		int sig;

		if (user_mode(regs)) {
		/*
		* This is an implicit supervisor-mode access from user
		* mode. Bypass all the kernel-mode recovery code and just
		* OOPS.
		*/
		goto oops;
		}

		/* Are we prepared to handle this kernel fault? */
		if (fixup_exception(regs, X86_TRAP_PF, error_code, address)) {
		/*
		@@ -738,6 +747,7 @@ no_context(struct pt_regs *regs, unsigned long error_code,
		if (IS_ENABLED(CONFIG_EFI))
		efi_recover_from_page_fault(address);

		oops:
		/*
		* Oops. The kernel tried to access some bad page. We'll have to
		* terminate things with extreme prejudice:

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