Messages in this thread Patch in this message | | | From | Andy Lutomirski <> | Subject | [PATCH 10/13] x86/fault: Don't try to recover from an implicit supervisor access | Date | Mon, 19 Nov 2018 14:45:34 -0800 |
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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 away that causes this type of fault.
Signed-off-by: Andy Lutomirski <luto@kernel.org> --- arch/x86/mm/fault.c | 10 ++++++++++ 1 file changed, 10 insertions(+)
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 6e18438c367f..092ed6b1df8a 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -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: -- 2.17.2
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