Hi! > Resuming from a suspend operation is showing a KASAN false positive > warning:
> KASAN instrumentation poisons the stack when entering a function and > unpoisons it when exiting the function. However, in the suspend path, > some functions never return, so their stack never gets unpoisoned, > resulting in stale KASAN shadow data which can cause later false > positive warnings like the one above. > > Reported-by: Scott Bauer <[email protected]> > Suggested-by: Dmitry Vyukov <[email protected]> > Signed-off-by: Josh Poimboeuf <[email protected]> Acked-by: Pavel Machek <[email protected]> > --- > arch/x86/kernel/acpi/wakeup_64.S | 16 ++++++++++++++++ > 1 file changed, 16 insertions(+) > > diff --git a/arch/x86/kernel/acpi/wakeup_64.S > b/arch/x86/kernel/acpi/wakeup_64.S > index 169963f..1df9b75 100644 > --- a/arch/x86/kernel/acpi/wakeup_64.S > +++ b/arch/x86/kernel/acpi/wakeup_64.S > @@ -109,6 +109,22 @@ ENTRY(do_suspend_lowlevel) > movq pt_regs_r14(%rax), %r14 > movq pt_regs_r15(%rax), %r15 > > +#ifdef CONFIG_KASAN > + /* > + * The suspend path may have poisoned some areas deeper in the stack, > + * which we now need to unpoison. > + * > + * We can't call kasan_unpoison_task_stack_below() because it uses %gs > + * for 'current', which hasn't been set up yet. Instead, calculate the > + * stack range manually and call kasan_unpoison_shadow(). > + */ > + movq %rsp, %rdi > + andq $CURRENT_MASK, %rdi > + movq %rsp, %rsi > + xorq %rdi, %rsi > + call kasan_unpoison_shadow > +#endif Well... you may want to add note to kasan_unpoison_shadow() /* * This is called by early resume code, with cpu not yer properly * resumed. In particular, %gs may not be set up, and thus current * is not available. */ Thanks, Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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