On 12/01/2016 02:10 AM, Josh Poimboeuf wrote: > 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 false positive > warnings like the one above. > > Reported-by: Scott Bauer <scott.ba...@intel.com> > Tested-by: Scott Bauer <scott.ba...@intel.com> > Signed-off-by: Josh Poimboeuf <jpoim...@redhat.com> > --- > arch/x86/kernel/acpi/sleep.c | 3 +++ > include/linux/kasan.h | 7 +++++++ > 2 files changed, 10 insertions(+) > > diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c > index 4858733..62bd046 100644 > --- a/arch/x86/kernel/acpi/sleep.c > +++ b/arch/x86/kernel/acpi/sleep.c > @@ -115,6 +115,9 @@ int x86_acpi_suspend_lowlevel(void) > pause_graph_tracing(); > do_suspend_lowlevel(); > unpause_graph_tracing(); > + > + kasan_unpoison_stack_below_sp(); > + I think this might be too late. We may hit stale poison in the first C function called after resume (restore_processor_state()). Thus the shadow must be unpoisoned prior such call, i.e. somewhere in do_suspend_lowlevel() after .Lresume_point.
