[PATCH] kasan: fix kasan_check_read/write definitions

[PATCH] kasan: fix kasan_check_read/write definitions

[Arnd Bergmann]

Building little-endian allmodconfig kernels on arm64 started failing
with the generated atomic.h implementation, since we now try to call
kasan helpers from the EFI stub:

aarch64-linux-gnu-ld: drivers/firmware/efi/libstub/arm-stub.stub.o: in function `atomic_set':
include/generated/atomic-instrumented.h:44: undefined reference to `__efistub_kasan_check_write'

I suspect that we get similar problems in other files that explicitly
disable KASAN for some reason but call atomic_t based helper functions.

We can fix this by checking the predefined __SANITIZE_ADDRESS__ macro
that the compiler sets instead of checking CONFIG_KASAN, but this in turn
requires a small hack in mm/kasan/common.c so we do see the extern
declaration there instead of the inline function.

Fixes: b1864b828644 ("locking/atomics: build atomic headers as required")
Reported-by: Anders Roxell <anders.roxell@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 include/linux/kasan-checks.h | 2 +-
 mm/kasan/common.c            | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/include/linux/kasan-checks.h b/include/linux/kasan-checks.h
index d314150658a4..a61dc075e2ce 100644
--- a/include/linux/kasan-checks.h
+++ b/include/linux/kasan-checks.h
@@ -2,7 +2,7 @@
 #ifndef _LINUX_KASAN_CHECKS_H
 #define _LINUX_KASAN_CHECKS_H
 
-#ifdef CONFIG_KASAN
+#if defined(__SANITIZE_ADDRESS__) || defined(__KASAN_INTERNAL)
 void kasan_check_read(const volatile void *p, unsigned int size);
 void kasan_check_write(const volatile void *p, unsigned int size);
 #else
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index 03d5d1374ca7..51a7932c33a3 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -14,6 +14,8 @@
  *
  */
 
+#define __KASAN_INTERNAL
+
 #include <linux/export.h>
 #include <linux/interrupt.h>
 #include <linux/init.h>
-- 
2.20.0

Re: [PATCH] kasan: fix kasan_check_read/write definitions

[Dmitry Vyukov]

On Tue, Dec 11, 2018 at 2:35 PM Arnd Bergmann <arnd@arndb.de> wrote:
>
> Building little-endian allmodconfig kernels on arm64 started failing
> with the generated atomic.h implementation, since we now try to call
> kasan helpers from the EFI stub:
>
> aarch64-linux-gnu-ld: drivers/firmware/efi/libstub/arm-stub.stub.o: in function `atomic_set':
> include/generated/atomic-instrumented.h:44: undefined reference to `__efistub_kasan_check_write'
>
> I suspect that we get similar problems in other files that explicitly
> disable KASAN for some reason but call atomic_t based helper functions.
>
> We can fix this by checking the predefined __SANITIZE_ADDRESS__ macro
> that the compiler sets instead of checking CONFIG_KASAN, but this in turn
> requires a small hack in mm/kasan/common.c so we do see the extern
> declaration there instead of the inline function.


Alexander, I think you are doing a similar thing for similar reasons
in KMSAN patch (see KMSAN_CHECK_ATOMIC_PARAMS):
https://github.com/google/kmsan/commit/17ebbfe19624c84adf79b0e5a74fd258c49ff12b
Namely, non-KMSAN-instrumented files must not get KMSAN callbacks from
atomics too.

Arnd patch does it the other way around: non-instrumented files need
to opt-in instead of opt-out.
Let's settle on a common way to do this, so that we can use it
consistently across all tools.



> Fixes: b1864b828644 ("locking/atomics: build atomic headers as required")
> Reported-by: Anders Roxell <anders.roxell@linaro.org>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  include/linux/kasan-checks.h | 2 +-
>  mm/kasan/common.c            | 2 ++
>  2 files changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/kasan-checks.h b/include/linux/kasan-checks.h
> index d314150658a4..a61dc075e2ce 100644
> --- a/include/linux/kasan-checks.h
> +++ b/include/linux/kasan-checks.h
> @@ -2,7 +2,7 @@
>  #ifndef _LINUX_KASAN_CHECKS_H
>  #define _LINUX_KASAN_CHECKS_H
>
> -#ifdef CONFIG_KASAN
> +#if defined(__SANITIZE_ADDRESS__) || defined(__KASAN_INTERNAL)
>  void kasan_check_read(const volatile void *p, unsigned int size);
>  void kasan_check_write(const volatile void *p, unsigned int size);
>  #else
> diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> index 03d5d1374ca7..51a7932c33a3 100644
> --- a/mm/kasan/common.c
> +++ b/mm/kasan/common.c
> @@ -14,6 +14,8 @@
>   *
>   */
>
> +#define __KASAN_INTERNAL
> +
>  #include <linux/export.h>
>  #include <linux/interrupt.h>
>  #include <linux/init.h>
> --
> 2.20.0
>

Re: [PATCH] kasan: fix kasan_check_read/write definitions

[Alexander Potapenko]

On Tue, Dec 11, 2018 at 2:45 PM Dmitry Vyukov <dvyukov@google.com> wrote:
>
> On Tue, Dec 11, 2018 at 2:35 PM Arnd Bergmann <arnd@arndb.de> wrote:
> >
> > Building little-endian allmodconfig kernels on arm64 started failing
> > with the generated atomic.h implementation, since we now try to call
> > kasan helpers from the EFI stub:
> >
> > aarch64-linux-gnu-ld: drivers/firmware/efi/libstub/arm-stub.stub.o: in function `atomic_set':
> > include/generated/atomic-instrumented.h:44: undefined reference to `__efistub_kasan_check_write'
> >
> > I suspect that we get similar problems in other files that explicitly
> > disable KASAN for some reason but call atomic_t based helper functions.
> >
> > We can fix this by checking the predefined __SANITIZE_ADDRESS__ macro
> > that the compiler sets instead of checking CONFIG_KASAN, but this in turn
> > requires a small hack in mm/kasan/common.c so we do see the extern
> > declaration there instead of the inline function.
>
>
> Alexander, I think you are doing a similar thing for similar reasons
> in KMSAN patch (see KMSAN_CHECK_ATOMIC_PARAMS):
> https://github.com/google/kmsan/commit/17ebbfe19624c84adf79b0e5a74fd258c49ff12b
> Namely, non-KMSAN-instrumented files must not get KMSAN callbacks from
> atomics too.
I'll need to double-check, but it occurs to me that we won't need
additional hooks for atomics in KMSAN - the compiler instrumentation
should suffice.

> Arnd patch does it the other way around: non-instrumented files need
> to opt-in instead of opt-out.
Shouldn't we put __SANITIZE_ADDRESS__ somewhere into mm/kasan/kasan.h then?
> Let's settle on a common way to do this, so that we can use it
> consistently across all tools.
>
>
>
> > Fixes: b1864b828644 ("locking/atomics: build atomic headers as required")
> > Reported-by: Anders Roxell <anders.roxell@linaro.org>
> > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> > ---
> >  include/linux/kasan-checks.h | 2 +-
> >  mm/kasan/common.c            | 2 ++
> >  2 files changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/linux/kasan-checks.h b/include/linux/kasan-checks.h
> > index d314150658a4..a61dc075e2ce 100644
> > --- a/include/linux/kasan-checks.h
> > +++ b/include/linux/kasan-checks.h
> > @@ -2,7 +2,7 @@
> >  #ifndef _LINUX_KASAN_CHECKS_H
> >  #define _LINUX_KASAN_CHECKS_H
> >
> > -#ifdef CONFIG_KASAN
> > +#if defined(__SANITIZE_ADDRESS__) || defined(__KASAN_INTERNAL)
> >  void kasan_check_read(const volatile void *p, unsigned int size);
> >  void kasan_check_write(const volatile void *p, unsigned int size);
> >  #else
> > diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> > index 03d5d1374ca7..51a7932c33a3 100644
> > --- a/mm/kasan/common.c
> > +++ b/mm/kasan/common.c
> > @@ -14,6 +14,8 @@
> >   *
> >   */
> >
> > +#define __KASAN_INTERNAL
> > +
> >  #include <linux/export.h>
> >  #include <linux/interrupt.h>
> >  #include <linux/init.h>
> > --
> > 2.20.0
> >



-- 
Alexander Potapenko
Software Engineer

Google Germany GmbH
Erika-Mann-Straße, 33
80636 München

Geschäftsführer: Paul Manicle, Halimah DeLaine Prado
Registergericht und -nummer: Hamburg, HRB 86891
Sitz der Gesellschaft: Hamburg

Re: [PATCH] kasan: fix kasan_check_read/write definitions

[Dmitry Vyukov]

On Tue, Dec 11, 2018 at 11:25 PM Alexander Potapenko <glider@google.com> wrote:
> > > Building little-endian allmodconfig kernels on arm64 started failing
> > > with the generated atomic.h implementation, since we now try to call
> > > kasan helpers from the EFI stub:
> > >
> > > aarch64-linux-gnu-ld: drivers/firmware/efi/libstub/arm-stub.stub.o: in function `atomic_set':
> > > include/generated/atomic-instrumented.h:44: undefined reference to `__efistub_kasan_check_write'
> > >
> > > I suspect that we get similar problems in other files that explicitly
> > > disable KASAN for some reason but call atomic_t based helper functions.
> > >
> > > We can fix this by checking the predefined __SANITIZE_ADDRESS__ macro
> > > that the compiler sets instead of checking CONFIG_KASAN, but this in turn
> > > requires a small hack in mm/kasan/common.c so we do see the extern
> > > declaration there instead of the inline function.
> >
> >
> > Alexander, I think you are doing a similar thing for similar reasons
> > in KMSAN patch (see KMSAN_CHECK_ATOMIC_PARAMS):
> > https://github.com/google/kmsan/commit/17ebbfe19624c84adf79b0e5a74fd258c49ff12b
> > Namely, non-KMSAN-instrumented files must not get KMSAN callbacks from
> > atomics too.
> I'll need to double-check, but it occurs to me that we won't need
> additional hooks for atomics in KMSAN - the compiler instrumentation
> should suffice.

Compiler asm instrumentation will only insert conservative
initialization, but not checks of arguments, right?
I mean these checks are optional in the sense that it's only false
negatives, but since we already have them and they don't seem to lead
to false positives, why do we want to remove them?


> > Arnd patch does it the other way around: non-instrumented files need
> > to opt-in instead of opt-out.
> Shouldn't we put __SANITIZE_ADDRESS__ somewhere into mm/kasan/kasan.h then?
> > Let's settle on a common way to do this, so that we can use it
> > consistently across all tools.
> >
> >
> >
> > > Fixes: b1864b828644 ("locking/atomics: build atomic headers as required")
> > > Reported-by: Anders Roxell <anders.roxell@linaro.org>
> > > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> > > ---
> > >  include/linux/kasan-checks.h | 2 +-
> > >  mm/kasan/common.c            | 2 ++
> > >  2 files changed, 3 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/include/linux/kasan-checks.h b/include/linux/kasan-checks.h
> > > index d314150658a4..a61dc075e2ce 100644
> > > --- a/include/linux/kasan-checks.h
> > > +++ b/include/linux/kasan-checks.h
> > > @@ -2,7 +2,7 @@
> > >  #ifndef _LINUX_KASAN_CHECKS_H
> > >  #define _LINUX_KASAN_CHECKS_H
> > >
> > > -#ifdef CONFIG_KASAN
> > > +#if defined(__SANITIZE_ADDRESS__) || defined(__KASAN_INTERNAL)
> > >  void kasan_check_read(const volatile void *p, unsigned int size);
> > >  void kasan_check_write(const volatile void *p, unsigned int size);
> > >  #else
> > > diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> > > index 03d5d1374ca7..51a7932c33a3 100644
> > > --- a/mm/kasan/common.c
> > > +++ b/mm/kasan/common.c
> > > @@ -14,6 +14,8 @@
> > >   *
> > >   */
> > >
> > > +#define __KASAN_INTERNAL
> > > +
> > >  #include <linux/export.h>
> > >  #include <linux/interrupt.h>
> > >  #include <linux/init.h>
> > > --
> > > 2.20.0
> > >
>
>
>
> --
> Alexander Potapenko
> Software Engineer
>
> Google Germany GmbH
> Erika-Mann-Straße, 33
> 80636 München
>
> Geschäftsführer: Paul Manicle, Halimah DeLaine Prado
> Registergericht und -nummer: Hamburg, HRB 86891
> Sitz der Gesellschaft: Hamburg

Re: [PATCH] kasan: fix kasan_check_read/write definitions

[Nathan Chancellor]

On Tue, Dec 11, 2018 at 02:34:35PM +0100, Arnd Bergmann wrote:
> Building little-endian allmodconfig kernels on arm64 started failing
> with the generated atomic.h implementation, since we now try to call
> kasan helpers from the EFI stub:
> 
> aarch64-linux-gnu-ld: drivers/firmware/efi/libstub/arm-stub.stub.o: in function `atomic_set':
> include/generated/atomic-instrumented.h:44: undefined reference to `__efistub_kasan_check_write'
> 
> I suspect that we get similar problems in other files that explicitly
> disable KASAN for some reason but call atomic_t based helper functions.
> 
> We can fix this by checking the predefined __SANITIZE_ADDRESS__ macro
> that the compiler sets instead of checking CONFIG_KASAN, but this in turn
> requires a small hack in mm/kasan/common.c so we do see the extern
> declaration there instead of the inline function.
> 
> Fixes: b1864b828644 ("locking/atomics: build atomic headers as required")
> Reported-by: Anders Roxell <anders.roxell@linaro.org>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  include/linux/kasan-checks.h | 2 +-
>  mm/kasan/common.c            | 2 ++
>  2 files changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/kasan-checks.h b/include/linux/kasan-checks.h
> index d314150658a4..a61dc075e2ce 100644
> --- a/include/linux/kasan-checks.h
> +++ b/include/linux/kasan-checks.h
> @@ -2,7 +2,7 @@
>  #ifndef _LINUX_KASAN_CHECKS_H
>  #define _LINUX_KASAN_CHECKS_H
>  
> -#ifdef CONFIG_KASAN
> +#if defined(__SANITIZE_ADDRESS__) || defined(__KASAN_INTERNAL)
>  void kasan_check_read(const volatile void *p, unsigned int size);
>  void kasan_check_write(const volatile void *p, unsigned int size);
>  #else
> diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> index 03d5d1374ca7..51a7932c33a3 100644
> --- a/mm/kasan/common.c
> +++ b/mm/kasan/common.c
> @@ -14,6 +14,8 @@
>   *
>   */
>  
> +#define __KASAN_INTERNAL
> +
>  #include <linux/export.h>
>  #include <linux/interrupt.h>
>  #include <linux/init.h>
> -- 
> 2.20.0
> 

Hi all,

Was there any other movement on this patch? I am noticing this fail as
well and I have applied this patch in the meantime; it would be nice for
it to be merged so I could drop it from my stack.

Thanks,
Nathan

Re: [PATCH] kasan: fix kasan_check_read/write definitions

[Dmitry Vyukov]

On Tue, Jan 8, 2019 at 3:27 AM Nathan Chancellor
<natechancellor@gmail.com> wrote:
>
> On Tue, Dec 11, 2018 at 02:34:35PM +0100, Arnd Bergmann wrote:
> > Building little-endian allmodconfig kernels on arm64 started failing
> > with the generated atomic.h implementation, since we now try to call
> > kasan helpers from the EFI stub:
> >
> > aarch64-linux-gnu-ld: drivers/firmware/efi/libstub/arm-stub.stub.o: in function `atomic_set':
> > include/generated/atomic-instrumented.h:44: undefined reference to `__efistub_kasan_check_write'
> >
> > I suspect that we get similar problems in other files that explicitly
> > disable KASAN for some reason but call atomic_t based helper functions.
> >
> > We can fix this by checking the predefined __SANITIZE_ADDRESS__ macro
> > that the compiler sets instead of checking CONFIG_KASAN, but this in turn
> > requires a small hack in mm/kasan/common.c so we do see the extern
> > declaration there instead of the inline function.
> >
> > Fixes: b1864b828644 ("locking/atomics: build atomic headers as required")
> > Reported-by: Anders Roxell <anders.roxell@linaro.org>
> > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> > ---
> >  include/linux/kasan-checks.h | 2 +-
> >  mm/kasan/common.c            | 2 ++
> >  2 files changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/linux/kasan-checks.h b/include/linux/kasan-checks.h
> > index d314150658a4..a61dc075e2ce 100644
> > --- a/include/linux/kasan-checks.h
> > +++ b/include/linux/kasan-checks.h
> > @@ -2,7 +2,7 @@
> >  #ifndef _LINUX_KASAN_CHECKS_H
> >  #define _LINUX_KASAN_CHECKS_H
> >
> > -#ifdef CONFIG_KASAN
> > +#if defined(__SANITIZE_ADDRESS__) || defined(__KASAN_INTERNAL)
> >  void kasan_check_read(const volatile void *p, unsigned int size);
> >  void kasan_check_write(const volatile void *p, unsigned int size);
> >  #else
> > diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> > index 03d5d1374ca7..51a7932c33a3 100644
> > --- a/mm/kasan/common.c
> > +++ b/mm/kasan/common.c
> > @@ -14,6 +14,8 @@
> >   *
> >   */
> >
> > +#define __KASAN_INTERNAL
> > +
> >  #include <linux/export.h>
> >  #include <linux/interrupt.h>
> >  #include <linux/init.h>
> > --
> > 2.20.0
> >
>
> Hi all,
>
> Was there any other movement on this patch? I am noticing this fail as
> well and I have applied this patch in the meantime; it would be nice for
> it to be merged so I could drop it from my stack.

Alexander, ping, you wanted to double-check re KMSAN asm
instrumentation and then decide on a common approach for KASAN and
KMSAN.

Re: [PATCH] kasan: fix kasan_check_read/write definitions

[Dmitry Vyukov]

On Tue, Jan 8, 2019 at 3:27 AM Nathan Chancellor
<natechancellor@gmail.com> wrote:
>
> On Tue, Dec 11, 2018 at 02:34:35PM +0100, Arnd Bergmann wrote:
> > Building little-endian allmodconfig kernels on arm64 started failing
> > with the generated atomic.h implementation, since we now try to call
> > kasan helpers from the EFI stub:
> >
> > aarch64-linux-gnu-ld: drivers/firmware/efi/libstub/arm-stub.stub.o: in function `atomic_set':
> > include/generated/atomic-instrumented.h:44: undefined reference to `__efistub_kasan_check_write'
> >
> > I suspect that we get similar problems in other files that explicitly
> > disable KASAN for some reason but call atomic_t based helper functions.
> >
> > We can fix this by checking the predefined __SANITIZE_ADDRESS__ macro
> > that the compiler sets instead of checking CONFIG_KASAN, but this in turn
> > requires a small hack in mm/kasan/common.c so we do see the extern
> > declaration there instead of the inline function.
> >
> > Fixes: b1864b828644 ("locking/atomics: build atomic headers as required")
> > Reported-by: Anders Roxell <anders.roxell@linaro.org>
> > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> > ---
> >  include/linux/kasan-checks.h | 2 +-
> >  mm/kasan/common.c            | 2 ++
> >  2 files changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/linux/kasan-checks.h b/include/linux/kasan-checks.h
> > index d314150658a4..a61dc075e2ce 100644
> > --- a/include/linux/kasan-checks.h
> > +++ b/include/linux/kasan-checks.h
> > @@ -2,7 +2,7 @@
> >  #ifndef _LINUX_KASAN_CHECKS_H
> >  #define _LINUX_KASAN_CHECKS_H
> >
> > -#ifdef CONFIG_KASAN
> > +#if defined(__SANITIZE_ADDRESS__) || defined(__KASAN_INTERNAL)
> >  void kasan_check_read(const volatile void *p, unsigned int size);
> >  void kasan_check_write(const volatile void *p, unsigned int size);
> >  #else
> > diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> > index 03d5d1374ca7..51a7932c33a3 100644
> > --- a/mm/kasan/common.c
> > +++ b/mm/kasan/common.c
> > @@ -14,6 +14,8 @@
> >   *
> >   */
> >
> > +#define __KASAN_INTERNAL
> > +
> >  #include <linux/export.h>
> >  #include <linux/interrupt.h>
> >  #include <linux/init.h>
> > --
> > 2.20.0
> >
>
> Hi all,
>
> Was there any other movement on this patch? I am noticing this fail as
> well and I have applied this patch in the meantime; it would be nice for
> it to be merged so I could drop it from my stack.

Alexander, ping, you wanted to double-check re KMSAN asm
instrumentation and then decide on a common approach for KASAN and
KMSAN.

Re: [PATCH] kasan: fix kasan_check_read/write definitions

[Alexander Potapenko]

On Tue, Jan 8, 2019 at 5:51 AM Dmitry Vyukov <dvyukov@google.com> wrote:
>
> On Tue, Jan 8, 2019 at 3:27 AM Nathan Chancellor
> <natechancellor@gmail.com> wrote:
> >
> > On Tue, Dec 11, 2018 at 02:34:35PM +0100, Arnd Bergmann wrote:
> > > Building little-endian allmodconfig kernels on arm64 started failing
> > > with the generated atomic.h implementation, since we now try to call
> > > kasan helpers from the EFI stub:
> > >
> > > aarch64-linux-gnu-ld: drivers/firmware/efi/libstub/arm-stub.stub.o: in function `atomic_set':
> > > include/generated/atomic-instrumented.h:44: undefined reference to `__efistub_kasan_check_write'
> > >
> > > I suspect that we get similar problems in other files that explicitly
> > > disable KASAN for some reason but call atomic_t based helper functions.
> > >
> > > We can fix this by checking the predefined __SANITIZE_ADDRESS__ macro
> > > that the compiler sets instead of checking CONFIG_KASAN, but this in turn
> > > requires a small hack in mm/kasan/common.c so we do see the extern
> > > declaration there instead of the inline function.
> > >
> > > Fixes: b1864b828644 ("locking/atomics: build atomic headers as required")
> > > Reported-by: Anders Roxell <anders.roxell@linaro.org>
> > > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Alexander Potapenko <glider@google.com>
> > > ---
> > >  include/linux/kasan-checks.h | 2 +-
> > >  mm/kasan/common.c            | 2 ++
> > >  2 files changed, 3 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/include/linux/kasan-checks.h b/include/linux/kasan-checks.h
> > > index d314150658a4..a61dc075e2ce 100644
> > > --- a/include/linux/kasan-checks.h
> > > +++ b/include/linux/kasan-checks.h
> > > @@ -2,7 +2,7 @@
> > >  #ifndef _LINUX_KASAN_CHECKS_H
> > >  #define _LINUX_KASAN_CHECKS_H
> > >
> > > -#ifdef CONFIG_KASAN
> > > +#if defined(__SANITIZE_ADDRESS__) || defined(__KASAN_INTERNAL)
> > >  void kasan_check_read(const volatile void *p, unsigned int size);
> > >  void kasan_check_write(const volatile void *p, unsigned int size);
> > >  #else
> > > diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> > > index 03d5d1374ca7..51a7932c33a3 100644
> > > --- a/mm/kasan/common.c
> > > +++ b/mm/kasan/common.c
> > > @@ -14,6 +14,8 @@
> > >   *
> > >   */
> > >
> > > +#define __KASAN_INTERNAL
> > > +
> > >  #include <linux/export.h>
> > >  #include <linux/interrupt.h>
> > >  #include <linux/init.h>
> > > --
> > > 2.20.0
> > >
> >
> > Hi all,
> >
> > Was there any other movement on this patch? I am noticing this fail as
> > well and I have applied this patch in the meantime; it would be nice for
> > it to be merged so I could drop it from my stack.
>
> Alexander, ping, you wanted to double-check re KMSAN asm
> instrumentation and then decide on a common approach for KASAN and
> KMSAN.

I like Arnd's approach and will do the same for KMSAN.
Arnd, please go ahead submitting your patch.
The only possible issue I'm anticipating is that in the future we may
want to disable the checks in non-KASAN code (e.g. in arch/ or mm/),
so __KASAN_INTERNAL may not be the best name, but that's up to you.

-- 
Alexander Potapenko
Software Engineer

Google Germany GmbH
Erika-Mann-Straße, 33
80636 München

Geschäftsführer: Paul Manicle, Halimah DeLaine Prado
Registergericht und -nummer: Hamburg, HRB 86891
Sitz der Gesellschaft: Hamburg

Re: [PATCH] kasan: fix kasan_check_read/write definitions

[Alexander Potapenko]

On Tue, Jan 8, 2019 at 5:51 AM Dmitry Vyukov <dvyukov@google.com> wrote:
>
> On Tue, Jan 8, 2019 at 3:27 AM Nathan Chancellor
> <natechancellor@gmail.com> wrote:
> >
> > On Tue, Dec 11, 2018 at 02:34:35PM +0100, Arnd Bergmann wrote:
> > > Building little-endian allmodconfig kernels on arm64 started failing
> > > with the generated atomic.h implementation, since we now try to call
> > > kasan helpers from the EFI stub:
> > >
> > > aarch64-linux-gnu-ld: drivers/firmware/efi/libstub/arm-stub.stub.o: in function `atomic_set':
> > > include/generated/atomic-instrumented.h:44: undefined reference to `__efistub_kasan_check_write'
> > >
> > > I suspect that we get similar problems in other files that explicitly
> > > disable KASAN for some reason but call atomic_t based helper functions.
> > >
> > > We can fix this by checking the predefined __SANITIZE_ADDRESS__ macro
> > > that the compiler sets instead of checking CONFIG_KASAN, but this in turn
> > > requires a small hack in mm/kasan/common.c so we do see the extern
> > > declaration there instead of the inline function.
> > >
> > > Fixes: b1864b828644 ("locking/atomics: build atomic headers as required")
> > > Reported-by: Anders Roxell <anders.roxell@linaro.org>
> > > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Alexander Potapenko <glider@google.com>
> > > ---
> > >  include/linux/kasan-checks.h | 2 +-
> > >  mm/kasan/common.c            | 2 ++
> > >  2 files changed, 3 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/include/linux/kasan-checks.h b/include/linux/kasan-checks.h
> > > index d314150658a4..a61dc075e2ce 100644
> > > --- a/include/linux/kasan-checks.h
> > > +++ b/include/linux/kasan-checks.h
> > > @@ -2,7 +2,7 @@
> > >  #ifndef _LINUX_KASAN_CHECKS_H
> > >  #define _LINUX_KASAN_CHECKS_H
> > >
> > > -#ifdef CONFIG_KASAN
> > > +#if defined(__SANITIZE_ADDRESS__) || defined(__KASAN_INTERNAL)
> > >  void kasan_check_read(const volatile void *p, unsigned int size);
> > >  void kasan_check_write(const volatile void *p, unsigned int size);
> > >  #else
> > > diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> > > index 03d5d1374ca7..51a7932c33a3 100644
> > > --- a/mm/kasan/common.c
> > > +++ b/mm/kasan/common.c
> > > @@ -14,6 +14,8 @@
> > >   *
> > >   */
> > >
> > > +#define __KASAN_INTERNAL
> > > +
> > >  #include <linux/export.h>
> > >  #include <linux/interrupt.h>
> > >  #include <linux/init.h>
> > > --
> > > 2.20.0
> > >
> >
> > Hi all,
> >
> > Was there any other movement on this patch? I am noticing this fail as
> > well and I have applied this patch in the meantime; it would be nice for
> > it to be merged so I could drop it from my stack.
>
> Alexander, ping, you wanted to double-check re KMSAN asm
> instrumentation and then decide on a common approach for KASAN and
> KMSAN.

I like Arnd's approach and will do the same for KMSAN.
Arnd, please go ahead submitting your patch.
The only possible issue I'm anticipating is that in the future we may
want to disable the checks in non-KASAN code (e.g. in arch/ or mm/),
so __KASAN_INTERNAL may not be the best name, but that's up to you.

-- 
Alexander Potapenko
Software Engineer

Google Germany GmbH
Erika-Mann-Straße, 33
80636 München

Geschäftsführer: Paul Manicle, Halimah DeLaine Prado
Registergericht und -nummer: Hamburg, HRB 86891
Sitz der Gesellschaft: Hamburg

Re: [PATCH] kasan: fix kasan_check_read/write definitions

[Andrey Ryabinin]

On 12/11/18 4:34 PM, Arnd Bergmann wrote:
> Building little-endian allmodconfig kernels on arm64 started failing
> with the generated atomic.h implementation, since we now try to call
> kasan helpers from the EFI stub:
> 
> aarch64-linux-gnu-ld: drivers/firmware/efi/libstub/arm-stub.stub.o: in function `atomic_set':
> include/generated/atomic-instrumented.h:44: undefined reference to `__efistub_kasan_check_write'
> 
> I suspect that we get similar problems in other files that explicitly
> disable KASAN for some reason but call atomic_t based helper functions.
> 
> We can fix this by checking the predefined __SANITIZE_ADDRESS__ macro
> that the compiler sets instead of checking CONFIG_KASAN, but this in turn
> requires a small hack in mm/kasan/common.c so we do see the extern
> declaration there instead of the inline function.
> 
> Fixes: b1864b828644 ("locking/atomics: build atomic headers as required")
> Reported-by: Anders Roxell <anders.roxell@linaro.org>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---

Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>