Commit 33cd65e7 authored by Marco Elver's avatar Marco Elver Committed by Linus Torvalds
Browse files

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@google.com: 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@google.com


Reported-by: default avatarkernel test robot <rong.a.chen@intel.com>
Signed-off-by: default avatarMarco Elver <elver@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: default avatarAndrey Konovalov <andreyknvl@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Qian Cai <cai@lca.pw>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r//20200517011732.GE24705@shao2-debian/
Link: http://lkml.kernel.org/r/20200519182459.87166-1-elver@google.com


Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 380e5c1d

mm/kasan/Makefile

+8 −8
Original line number Diff line number Diff line
@@ -15,14 +15,14 @@ CFLAGS_REMOVE_tags_report.o = $(CC_FLAGS_FTRACE) 


# 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

mm/kasan/generic.c

+0 −1
Original line number Diff line number Diff line
@@ -15,7 +15,6 @@ 
 */



#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#define DISABLE_BRANCH_PROFILING



#include <linux/export.h>

#include <linux/interrupt.h>

mm/kasan/tags.c

+0 −1
Original line number Diff line number Diff line
@@ -12,7 +12,6 @@ 
 */



#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#define DISABLE_BRANCH_PROFILING



#include <linux/export.h>

#include <linux/interrupt.h>

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