| From fa032de1a37162fecbedf5d8dbaa31835da271ae Mon Sep 17 00:00:00 2001 |
| From: Qian Cai <cai@lca.pw> |
| Date: Fri, 1 Feb 2019 14:20:20 -0800 |
| Subject: 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-cai@lca.pw |
| Signed-off-by: Qian Cai <cai@lca.pw> |
| Cc: Thomas Gleixner <tglx@linutronix.de> |
| Cc: Ingo Molnar <mingo@redhat.com> |
| Cc: Borislav Petkov <bp@alien8.de> |
| Cc: "H. Peter Anvin" <hpa@zytor.com> |
| Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> |
| Cc: Alexander Potapenko <glider@google.com> |
| Cc: Dmitry Vyukov <dvyukov@google.com> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| arch/x86/include/asm/page_64_types.h | 4 ++++ |
| 1 file changed, 4 insertions(+) |
| |
| diff --git a/arch/x86/include/asm/page_64_types.h b/arch/x86/include/asm/page_64_types.h |
| index b99d497e342d..0b6352aabbd3 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 |
| -- |
| 2.19.1 |
| |