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| author | Qian Cai <cai@lca.pw> | 2019-02-01 23:20:20 +0100 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-02-02 00:46:23 +0100 |
| commit | a8e911d13540487942d53137c156bd7707f66e5d (patch) | |
| tree | de592d5ac114fc0669d23274141c3115ccda268f /arch | |
| parent | mm/hugetlb.c: teach follow_hugetlb_page() to handle FOLL_NOWAIT (diff) | |
| download | linux-a8e911d13540487942d53137c156bd7707f66e5d.tar.xz linux-a8e911d13540487942d53137c156bd7707f66e5d.zip | |
x86_64: increase stack size for KASAN_EXTRA
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>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/include/asm/page_64_types.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/x86/include/asm/page_64_types.h b/arch/x86/include/asm/page_64_types.h index 8f657286d599..0ce558a8150d 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 |