On Fri, 22 May 2020 at 00:11, Qian Cai <cai@xxxxxx> wrote: > > On Tue, May 19, 2020 at 08:24:59PM +0200, 'Marco Elver' via kasan-dev wrote: > > 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. > > > > Link: https://lore.kernel.org/lkml/20200517011732.GE24705@shao2-debian/ > > Reported-by: kernel test robot <rong.a.chen@xxxxxxxxx> > > Signed-off-by: Marco Elver <elver@xxxxxxxxxx> > > --- > > mm/kasan/Makefile | 16 ++++++++-------- > > mm/kasan/generic.c | 1 - > > 2 files changed, 8 insertions(+), 9 deletions(-) > > > > diff --git a/mm/kasan/Makefile b/mm/kasan/Makefile > > index 434d503a6525..de3121848ddf 100644 > > --- a/mm/kasan/Makefile > > +++ b/mm/kasan/Makefile > > @@ -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) > > mm/kasan/tags.c:15:9: warning: 'DISABLE_BRANCH_PROFILING' macro redefined [-Wmacro-redefined] > #define DISABLE_BRANCH_PROFILING > ^ > <command line>:6:9: note: previous definition is here > #define DISABLE_BRANCH_PROFILING 1 > ^ > > This? > > diff --git a/mm/kasan/tags.c b/mm/kasan/tags.c > index 25b7734e7013..8a959fdd30e3 100644 > --- a/mm/kasan/tags.c > +++ b/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> > I missed this one, thanks! Added this to v2. v2: https://lkml.kernel.org/r/20200522075207.157349-1-elver@xxxxxxxxxx
