On Thu, Feb 21, 2019 at 12:43:23AM -0500, Sasha Levin wrote: > This is a note to let you know that I've just added the patch titled > > x86_64: increase stack size for KASAN_EXTRA > > to the 4.20-stable tree which can be found at: > > http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary > > The filename of the patch is: > x86_64-increase-stack-size-for-kasan_extra.patch > and it can be found in the queue-4.20 subdirectory. > > If you, or anyone else, feels it should not be added to the stable tree, > please let <sta...@vger.kernel.org> know about it. > > > > commit 67fd2fd35761d6bb8dcebe5070960c2f0baaef69 > Author: Qian Cai <c...@lca.pw> > Date: Fri Feb 1 14:20:20 2019 -0800 > > x86_64: increase stack size for KASAN_EXTRA > > [ Upstream commit a8e911d13540487942d53137c156bd7707f66e5d ] > > If the kernel is configured with KASAN_EXTRA, the stack size is > increasted significantly because this option sets "-fstack-reuse" to > "none" in GCC [1]. As a result, it triggers stack overrun quite often > with 32k stack size compiled using GCC 8. For example, this reproducer > > > https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/syscalls/madvise/madvise06.c > > triggers a "corrupted stack end detected inside scheduler" very reliably > with CONFIG_SCHED_STACK_END_CHECK enabled. > > There are just too many functions that could have a large stack with > KASAN_EXTRA due to large local variables that have been called over and > over again without being able to reuse the stacks. Some noticiable ones > are > > size > 7648 shrink_page_list > 3584 xfs_rmap_convert > 3312 migrate_page_move_mapping > 3312 dev_ethtool > 3200 migrate_misplaced_transhuge_page > 3168 copy_process > > There are other 49 functions are over 2k in size while compiling kernel > with "-Wframe-larger-than=" even with a related minimal config on this > machine. Hence, it is too much work to change Makefiles for each object > to compile without "-fsanitize-address-use-after-scope" individually. > > [1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81715#c23 > > Although there is a patch in GCC 9 to help the situation, GCC 9 probably > won't be released in a few months and then it probably take another > 6-month to 1-year for all major distros to include it as a default. > Hence, the stack usage with KASAN_EXTRA can be revisited again in 2020 > when GCC 9 is everywhere. Until then, this patch will help users avoid > stack overrun. > > This has already been fixed for arm64 for the same reason via > 6e8830674ea ("arm64: kasan: Increase stack size for KASAN_EXTRA"). > > Link: http://lkml.kernel.org/r/20190109215209.2903-1-...@lca.pw > Signed-off-by: Qian Cai <c...@lca.pw> > Cc: Thomas Gleixner <t...@linutronix.de> > Cc: Ingo Molnar <mi...@redhat.com> > Cc: Borislav Petkov <b...@alien8.de> > Cc: "H. Peter Anvin" <h...@zytor.com> > Cc: Andrey Ryabinin <aryabi...@virtuozzo.com> > Cc: Alexander Potapenko <gli...@google.com> > Cc: Dmitry Vyukov <dvyu...@google.com> > Signed-off-by: Andrew Morton <a...@linux-foundation.org> > Signed-off-by: Linus Torvalds <torva...@linux-foundation.org> > Signed-off-by: Sasha Levin <sas...@kernel.org> > > diff --git a/arch/x86/include/asm/page_64_types.h > b/arch/x86/include/asm/page_64_types.h > index 8f657286d599a..0ce558a8150d3 100644 > --- a/arch/x86/include/asm/page_64_types.h > +++ b/arch/x86/include/asm/page_64_types.h > @@ -7,7 +7,11 @@ > #endif > > #ifdef CONFIG_KASAN > +#ifdef CONFIG_KASAN_EXTRA > +#define KASAN_STACK_ORDER 2 > +#else > #define KASAN_STACK_ORDER 1 > +#endif > #else > #define KASAN_STACK_ORDER 0 > #endif
This looks like it is also relevant for 4.19.y so I have queued it up there too. greg k-h
