From: Marco Elver <elver@xxxxxxxxxx> Subject: kasan: disable branch tracing for core runtime During early boot, while KASAN is not yet initialized, it is possible to enter reporting code-path and end up in kasan_report(). While uninitialized, the branch there prevents generating any reports, however, under certain circumstances when branches are being traced (TRACE_BRANCH_PROFILING), we may recurse deep enough to cause kernel reboots without warning. To prevent similar issues in future, we should disable branch tracing for the core runtime. [elver@xxxxxxxxxx: remove duplicate DISABLE_BRANCH_PROFILING, per Qian Cai] Link: https://lore.kernel.org/lkml/20200517011732.GE24705@shao2-debian/ Link: http://lkml.kernel.org/r/20200522075207.157349-1-elver@xxxxxxxxxx Link: http://lkml.kernel.org/r//20200517011732.GE24705@shao2-debian/ Link: http://lkml.kernel.org/r/20200519182459.87166-1-elver@xxxxxxxxxx Signed-off-by: Marco Elver <elver@xxxxxxxxxx> Reported-by: kernel test robot <rong.a.chen@xxxxxxxxx> Reviewed-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Cc: Alexander Potapenko <glider@xxxxxxxxxx> Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> Cc: Qian Cai <cai@xxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/kasan/Makefile | 16 ++++++++-------- mm/kasan/generic.c | 1 - mm/kasan/tags.c | 1 - 3 files changed, 8 insertions(+), 10 deletions(-) --- a/mm/kasan/generic.c~kasan-disable-branch-tracing-for-core-runtime +++ a/mm/kasan/generic.c @@ -15,7 +15,6 @@ */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt -#define DISABLE_BRANCH_PROFILING #include <linux/export.h> #include <linux/interrupt.h> --- a/mm/kasan/Makefile~kasan-disable-branch-tracing-for-core-runtime +++ a/mm/kasan/Makefile @@ -15,14 +15,14 @@ CFLAGS_REMOVE_tags_report.o = $(CC_FLAGS # Function splitter causes unnecessary splits in __asan_load1/__asan_store1 # see: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63533 -CFLAGS_common.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -CFLAGS_generic.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -CFLAGS_generic_report.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -CFLAGS_init.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -CFLAGS_quarantine.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -CFLAGS_report.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -CFLAGS_tags.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -CFLAGS_tags_report.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) +CFLAGS_common.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING +CFLAGS_generic.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING +CFLAGS_generic_report.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING +CFLAGS_init.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING +CFLAGS_quarantine.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING +CFLAGS_report.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING +CFLAGS_tags.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING +CFLAGS_tags_report.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING obj-$(CONFIG_KASAN) := common.o init.o report.o obj-$(CONFIG_KASAN_GENERIC) += generic.o generic_report.o quarantine.o --- a/mm/kasan/tags.c~kasan-disable-branch-tracing-for-core-runtime +++ a/mm/kasan/tags.c @@ -12,7 +12,6 @@ */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt -#define DISABLE_BRANCH_PROFILING #include <linux/export.h> #include <linux/interrupt.h> _
