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| author | Arnd Bergmann <arnd@arndb.de> | 2019-02-28 16:21:58 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-03-01 09:02:33 -0800 |
| commit | 6baec880d7a53cbc2841123e56ee31e830df9b49 (patch) | |
| tree | 0d3b8aa38b8c1193677358b0e8ab4232cc24209c | |
| parent | 7d762d69145a54d169f58e56d6dac57a5508debc (diff) | |
| download | linux-6baec880d7a53cbc2841123e56ee31e830df9b49.tar.bz2 | |
kasan: turn off asan-stack for clang-8 and earlier
Building an arm64 allmodconfig kernel with clang results in over 140
warnings about overly large stack frames, the worst ones being:
drivers/gpu/drm/panel/panel-sitronix-st7789v.c:196:12: error: stack frame size of 20224 bytes in function 'st7789v_prepare'
drivers/video/fbdev/omap2/omapfb/displays/panel-tpo-td028ttec1.c:196:12: error: stack frame size of 13120 bytes in function 'td028ttec1_panel_enable'
drivers/usb/host/max3421-hcd.c:1395:1: error: stack frame size of 10048 bytes in function 'max3421_spi_thread'
drivers/net/wan/slic_ds26522.c:209:12: error: stack frame size of 9664 bytes in function 'slic_ds26522_probe'
drivers/crypto/ccp/ccp-ops.c:2434:5: error: stack frame size of 8832 bytes in function 'ccp_run_cmd'
drivers/media/dvb-frontends/stv0367.c:1005:12: error: stack frame size of 7840 bytes in function 'stv0367ter_algo'
None of these happen with gcc today, and almost all of these are the
result of a single known issue in llvm. Hopefully it will eventually
get fixed with the clang-9 release.
In the meantime, the best idea I have is to turn off asan-stack for
clang-8 and earlier, so we can produce a kernel that is safe to run.
I have posted three patches that address the frame overflow warnings
that are not addressed by turning off asan-stack, so in combination with
this change, we get much closer to a clean allmodconfig build, which in
turn is necessary to do meaningful build regression testing.
It is still possible to turn on the CONFIG_ASAN_STACK option on all
versions of clang, and it's always enabled for gcc, but when
CONFIG_COMPILE_TEST is set, the option remains invisible, so
allmodconfig and randconfig builds (which are normally done with a
forced CONFIG_COMPILE_TEST) will still result in a mostly clean build.
Link: http://lkml.kernel.org/r/20190222222950.3997333-1-arnd@arndb.de
Link: https://bugs.llvm.org/show_bug.cgi?id=38809
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Qian Cai <cai@lca.pw>
Reviewed-by: Mark Brown <broonie@kernel.org>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Kostya Serebryany <kcc@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | lib/Kconfig.kasan | 22 | ||||
| -rw-r--r-- | scripts/Makefile.kasan | 2 |
2 files changed, 23 insertions, 1 deletions
diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan index d8c474b6691e..9737059ec58b 100644 --- a/lib/Kconfig.kasan +++ b/lib/Kconfig.kasan @@ -113,6 +113,28 @@ config KASAN_INLINE endchoice +config KASAN_STACK_ENABLE + bool "Enable stack instrumentation (unsafe)" if CC_IS_CLANG && !COMPILE_TEST + default !(CLANG_VERSION < 90000) + depends on KASAN + help + The LLVM stack address sanitizer has a know problem that + causes excessive stack usage in a lot of functions, see + https://bugs.llvm.org/show_bug.cgi?id=38809 + Disabling asan-stack makes it safe to run kernels build + with clang-8 with KASAN enabled, though it loses some of + the functionality. + This feature is always disabled when compile-testing with clang-8 + or earlier to avoid cluttering the output in stack overflow + warnings, but clang-8 users can still enable it for builds without + CONFIG_COMPILE_TEST. On gcc and later clang versions it is + assumed to always be safe to use and enabled by default. + +config KASAN_STACK + int + default 1 if KASAN_STACK_ENABLE || CC_IS_GCC + default 0 + config KASAN_S390_4_LEVEL_PAGING bool "KASan: use 4-level paging" depends on KASAN && S390 diff --git a/scripts/Makefile.kasan b/scripts/Makefile.kasan index 25c259df8ffa..6deabedc67fc 100644 --- a/scripts/Makefile.kasan +++ b/scripts/Makefile.kasan @@ -26,7 +26,7 @@ else CFLAGS_KASAN := $(CFLAGS_KASAN_SHADOW) \ $(call cc-param,asan-globals=1) \ $(call cc-param,asan-instrumentation-with-call-threshold=$(call_threshold)) \ - $(call cc-param,asan-stack=1) \ + $(call cc-param,asan-stack=$(CONFIG_KASAN_STACK)) \ $(call cc-param,asan-use-after-scope=1) \ $(call cc-param,asan-instrument-allocas=1) endif |