On Tue, 23 Jul 2019 at 18:24, Mark Rutland <[email protected]> wrote: > > On Fri, Jul 19, 2019 at 03:28:18PM +0200, Marco Elver wrote: > > Adds a simple stack overflow test, to check the error being reported on > > an overflow. Without CONFIG_STACK_GUARD_PAGE, the result is typically > > some seemingly unrelated KASAN error message due to accessing random > > other memory. > > Can't we use the LKDTM_EXHAUST_STACK case to check this? > > I was also under the impression that the other KASAN self-tests weren't > fatal, and IIUC this will kill the kernel. > > Given that, and given this is testing non-KASAN functionality, I'm not > sure it makes sense to bundle this with the KASAN tests.
Thanks for pointing out LKDTM_EXHAUST_STACK. This patch can be dropped! -- Marco > Thanks, > Mark. > > > > > Signed-off-by: Marco Elver <[email protected]> > > Cc: Thomas Gleixner <[email protected]> > > Cc: Ingo Molnar <[email protected]> > > Cc: Borislav Petkov <[email protected]> > > Cc: "H. Peter Anvin" <[email protected]> > > Cc: Andrey Ryabinin <[email protected]> > > Cc: Alexander Potapenko <[email protected]> > > Cc: Dmitry Vyukov <[email protected]> > > Cc: Andrey Konovalov <[email protected]> > > Cc: Mark Rutland <[email protected]> > > Cc: Peter Zijlstra <[email protected]> > > Cc: [email protected] > > Cc: [email protected] > > Cc: [email protected] > > --- > > lib/test_kasan.c | 36 ++++++++++++++++++++++++++++++++++++ > > 1 file changed, 36 insertions(+) > > > > diff --git a/lib/test_kasan.c b/lib/test_kasan.c > > index b63b367a94e8..3092ec01189d 100644 > > --- a/lib/test_kasan.c > > +++ b/lib/test_kasan.c > > @@ -15,6 +15,7 @@ > > #include <linux/mman.h> > > #include <linux/module.h> > > #include <linux/printk.h> > > +#include <linux/sched/task_stack.h> > > #include <linux/slab.h> > > #include <linux/string.h> > > #include <linux/uaccess.h> > > @@ -709,6 +710,32 @@ static noinline void __init kmalloc_double_kzfree(void) > > kzfree(ptr); > > } > > > > +#ifdef CONFIG_STACK_GUARD_PAGE > > +static noinline void __init stack_overflow_via_recursion(void) > > +{ > > + volatile int n = 512; > > + > > + BUILD_BUG_ON(IS_ENABLED(CONFIG_STACK_GROWSUP)); > > + > > + /* About to overflow: overflow via alloca'd array and try to write. */ > > + if (!object_is_on_stack((void *)&n - n)) { > > + volatile char overflow[n]; > > + > > + overflow[0] = overflow[0]; > > + return; > > + } > > + > > + stack_overflow_via_recursion(); > > +} > > + > > +static noinline void __init kasan_stack_overflow(void) > > +{ > > + pr_info("stack overflow begin\n"); > > + stack_overflow_via_recursion(); > > + pr_info("stack overflow end\n"); > > +} > > +#endif > > + > > static int __init kmalloc_tests_init(void) > > { > > /* > > @@ -753,6 +780,15 @@ static int __init kmalloc_tests_init(void) > > kasan_bitops(); > > kmalloc_double_kzfree(); > > > > +#ifdef CONFIG_STACK_GUARD_PAGE > > + /* > > + * Only test with CONFIG_STACK_GUARD_PAGE, as without we get other > > + * random KASAN violations, due to accessing other random memory (we > > + * want to avoid actually corrupting memory in these tests). > > + */ > > + kasan_stack_overflow(); > > +#endif > > + > > kasan_restore_multi_shot(multishot); > > > > return -EAGAIN; > > -- > > 2.22.0.657.g960e92d24f-goog > > > > -- > You received this message because you are subscribed to the Google Groups > "kasan-dev" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/kasan-dev/20190723162403.GA56959%40lakrids.cambridge.arm.com.
