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* [PATCH] kasan: Disable branch tracing for core runtime
@ 2020-05-19 18:24 Marco Elver
  2020-05-19 21:05 ` Andrey Konovalov
       [not found] ` <20200521221133.GD6367@ovpn-112-192.phx2.redhat.com>
  0 siblings, 2 replies; 4+ messages in thread
From: Marco Elver @ 2020-05-19 18:24 UTC (permalink / raw)
  To: elver
  Cc: dvyukov, glider, andreyknvl, linux-kernel, kasan-dev, aryabinin,
	akpm, linux-mm, kernel test robot

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@intel.com>
Signed-off-by: Marco Elver <elver@google.com>
---
 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)
-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
diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
index 56ff8885fe2e..098a7dbaced6 100644
--- a/mm/kasan/generic.c
+++ b/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>
-- 
2.26.2.761.g0e0b3e54be-goog



^ permalink raw reply related	[flat|nested] 4+ messages in thread
* Re: [PATCH] kasan: Disable branch tracing for core runtime
  2020-05-19 18:24 [PATCH] kasan: Disable branch tracing for core runtime Marco Elver
@ 2020-05-19 21:05 ` Andrey Konovalov
  2020-05-20  0:09   ` Andrew Morton
       [not found] ` <20200521221133.GD6367@ovpn-112-192.phx2.redhat.com>
  1 sibling, 1 reply; 4+ messages in thread
From: Andrey Konovalov @ 2020-05-19 21:05 UTC (permalink / raw)
  To: Marco Elver
  Cc: Dmitry Vyukov, Alexander Potapenko, LKML, kasan-dev,
	Andrey Ryabinin, Andrew Morton, Linux Memory Management List,
	kernel test robot

On Tue, May 19, 2020 at 8:25 PM Marco Elver <elver@google.com> 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@intel.com>
> Signed-off-by: Marco Elver <elver@google.com>
> ---
>  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)
> -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
> diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
> index 56ff8885fe2e..098a7dbaced6 100644
> --- a/mm/kasan/generic.c
> +++ b/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>
> --
> 2.26.2.761.g0e0b3e54be-goog
>

Reviewed-by: Andrey Konovalov <andreyknvl@google.com>

Thanks!


^ permalink raw reply	[flat|nested] 4+ messages in thread
* Re: [PATCH] kasan: Disable branch tracing for core runtime
  2020-05-19 21:05 ` Andrey Konovalov
@ 2020-05-20  0:09   ` Andrew Morton
  0 siblings, 0 replies; 4+ messages in thread
From: Andrew Morton @ 2020-05-20  0:09 UTC (permalink / raw)
  To: Andrey Konovalov
  Cc: Marco Elver, Dmitry Vyukov, Alexander Potapenko, LKML, kasan-dev,
	Andrey Ryabinin, Linux Memory Management List, kernel test robot

On Tue, 19 May 2020 23:05:46 +0200 Andrey Konovalov <andreyknvl@google.com> wrote:

> On Tue, May 19, 2020 at 8:25 PM Marco Elver <elver@google.com> 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.
> >
> 
> ...
>
> Reviewed-by: Andrey Konovalov <andreyknvl@google.com>

Thanks, I queued this for 5.7.


^ permalink raw reply	[flat|nested] 4+ messages in thread
* Re: [PATCH] kasan: Disable branch tracing for core runtime
       [not found] ` <20200521221133.GD6367@ovpn-112-192.phx2.redhat.com>
@ 2020-05-22  7:54   ` Marco Elver
  0 siblings, 0 replies; 4+ messages in thread
From: Marco Elver @ 2020-05-22  7:54 UTC (permalink / raw)
  To: Qian Cai
  Cc: Dmitry Vyukov, Alexander Potapenko, Andrey Konovalov, LKML,
	kasan-dev, Andrey Ryabinin, Andrew Morton,
	Linux Memory Management List, kernel test robot

On Fri, 22 May 2020 at 00:11, Qian Cai <cai@lca.pw> 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@intel.com>
> > Signed-off-by: Marco Elver <elver@google.com>
> > ---
> >  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@google.com


^ permalink raw reply	[flat|nested] 4+ messages in thread
end of thread, other threads:[~2020-05-22  7:54 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2020-05-19 18:24 [PATCH] kasan: Disable branch tracing for core runtime Marco Elver
2020-05-19 21:05 ` Andrey Konovalov
2020-05-20  0:09   ` Andrew Morton
     [not found] ` <20200521221133.GD6367@ovpn-112-192.phx2.redhat.com>
2020-05-22  7:54   ` Marco Elver

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