LinuxLists.cc - [PATCH] kasan: fix build for CONFIG_KASAN_HW

2021-07-08 14:45:38

Subject: [PATCH] kasan: fix build for CONFIG_KASAN_HW_TAGS

When CONFIG_KASAN_HW_TAGS is selected, <linux/kasan.h> uses _RET_IP_,
but doesn't explicitly include <linux/kernel.h> where this is defined.

We used to get this via a transitive include, but since commit:

f39650de687e3576 ("kernel.h: split out panic and oops helpers")

... this is no longer the case, and so we get a build failure:

| CC arch/arm64/mm/kasan_init.o
| In file included from arch/arm64/mm/kasan_init.c:10:
| ./include/linux/kasan.h: In function 'kasan_slab_free':
| ./include/linux/kasan.h:211:39: error: '_RET_IP_' undeclared (first use in this function)
| 211 | return __kasan_slab_free(s, object, _RET_IP_, init);
| | ^~~~~~~~
| ./include/linux/kasan.h:211:39: note: each undeclared identifier is reported only once for each function it appears in
| ./include/linux/kasan.h: In function 'kasan_kfree_large':
| ./include/linux/kasan.h:219:28: error: '_RET_IP_' undeclared (first use in this function)
| 219 | __kasan_kfree_large(ptr, _RET_IP_);
| | ^~~~~~~~
| ./include/linux/kasan.h: In function 'kasan_slab_free_mempool':
| ./include/linux/kasan.h:226:34: error: '_RET_IP_' undeclared (first use in this function)
| 226 | __kasan_slab_free_mempool(ptr, _RET_IP_);
| | ^~~~~~~~
| ./include/linux/kasan.h: In function 'kasan_check_byte':
| ./include/linux/kasan.h:277:35: error: '_RET_IP_' undeclared (first use in this function)
| 277 | return __kasan_check_byte(addr, _RET_IP_);
| | ^~~~~~~~

Fix this by including <linux/kernel.h> explicitly.

Fixes: 6028bf777417 ("kernel.h: split out panic and oops helpers")
Signed-off-by: Mark Rutland <[email protected]>
Cc: Alexander Potapenko <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Andrey Konovalov <[email protected]>
Cc: Andrey Ryabinin <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: Will Deacon <[email protected]>
---
include/linux/kasan.h | 1 +
1 file changed, 1 insertion(+)

As a heads-up, there are some unrelated runtime issues with
CONFIG_KASAN_HW_TAGS and the recent arm64 string routines rework, which
I'm looking into now. If you boot-test with this applied, you should
expect to see those.

Andrew, I assume you'd be the one to pick this up?

Thanks,
Mark.

diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index 5310e217bd74..dd874a1ee862 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -3,6 +3,7 @@
#define _LINUX_KASAN_H

#include <linux/bug.h>
+#include <linux/kernel.h>
#include <linux/static_key.h>
#include <linux/types.h>

--
2.11.0

2021-07-10 19:27:12

by Andrey Konovalov

[permalink] [raw]

Subject: Re: [PATCH] kasan: fix build for CONFIG_KASAN_HW_TAGS

On Thu, Jul 8, 2021 at 4:44 PM Mark Rutland <[email protected]> wrote:
>
> When CONFIG_KASAN_HW_TAGS is selected, <linux/kasan.h> uses _RET_IP_,
> but doesn't explicitly include <linux/kernel.h> where this is defined.
>
> We used to get this via a transitive include, but since commit:
>
> f39650de687e3576 ("kernel.h: split out panic and oops helpers")
>
> ... this is no longer the case, and so we get a build failure:
>
> | CC arch/arm64/mm/kasan_init.o
> | In file included from arch/arm64/mm/kasan_init.c:10:
> | ./include/linux/kasan.h: In function 'kasan_slab_free':
> | ./include/linux/kasan.h:211:39: error: '_RET_IP_' undeclared (first use in this function)
> | 211 | return __kasan_slab_free(s, object, _RET_IP_, init);
> | | ^~~~~~~~
> | ./include/linux/kasan.h:211:39: note: each undeclared identifier is reported only once for each function it appears in
> | ./include/linux/kasan.h: In function 'kasan_kfree_large':
> | ./include/linux/kasan.h:219:28: error: '_RET_IP_' undeclared (first use in this function)
> | 219 | __kasan_kfree_large(ptr, _RET_IP_);
> | | ^~~~~~~~
> | ./include/linux/kasan.h: In function 'kasan_slab_free_mempool':
> | ./include/linux/kasan.h:226:34: error: '_RET_IP_' undeclared (first use in this function)
> | 226 | __kasan_slab_free_mempool(ptr, _RET_IP_);
> | | ^~~~~~~~
> | ./include/linux/kasan.h: In function 'kasan_check_byte':
> | ./include/linux/kasan.h:277:35: error: '_RET_IP_' undeclared (first use in this function)
> | 277 | return __kasan_check_byte(addr, _RET_IP_);
> | | ^~~~~~~~
>
> Fix this by including <linux/kernel.h> explicitly.

Hi Mark,

Marco already sent a fix for this. It should be in the mm tree.
(Although the link to it in the Andrew's notification email doesn't
work. But they rarely do :)

> As a heads-up, there are some unrelated runtime issues with
> CONFIG_KASAN_HW_TAGS and the recent arm64 string routines rework, which
> I'm looking into now. If you boot-test with this applied, you should
> expect to see those.

+Sam, +Robin

Looks like the new strlen routine is making accesses past the allocated buffer.

The guilty commit is 325a1de81287 ("arm64: Import updated version of
Cortex Strings' strlen").

Thanks!

2021-07-12 09:06:57

by Mark Rutland

[permalink] [raw]

Subject: Re: [PATCH] kasan: fix build for CONFIG_KASAN_HW_TAGS

On Sat, Jul 10, 2021 at 09:16:14PM +0200, Andrey Konovalov wrote:
> On Thu, Jul 8, 2021 at 4:44 PM Mark Rutland <[email protected]> wrote:
> >
> > When CONFIG_KASAN_HW_TAGS is selected, <linux/kasan.h> uses _RET_IP_,
> > but doesn't explicitly include <linux/kernel.h> where this is defined.
> >
> > We used to get this via a transitive include, but since commit:
> >
> > f39650de687e3576 ("kernel.h: split out panic and oops helpers")
> >
> > ... this is no longer the case, and so we get a build failure:
> >
> > | CC arch/arm64/mm/kasan_init.o
> > | In file included from arch/arm64/mm/kasan_init.c:10:
> > | ./include/linux/kasan.h: In function 'kasan_slab_free':
> > | ./include/linux/kasan.h:211:39: error: '_RET_IP_' undeclared (first use in this function)
> > | 211 | return __kasan_slab_free(s, object, _RET_IP_, init);
> > | | ^~~~~~~~
> > | ./include/linux/kasan.h:211:39: note: each undeclared identifier is reported only once for each function it appears in
> > | ./include/linux/kasan.h: In function 'kasan_kfree_large':
> > | ./include/linux/kasan.h:219:28: error: '_RET_IP_' undeclared (first use in this function)
> > | 219 | __kasan_kfree_large(ptr, _RET_IP_);
> > | | ^~~~~~~~
> > | ./include/linux/kasan.h: In function 'kasan_slab_free_mempool':
> > | ./include/linux/kasan.h:226:34: error: '_RET_IP_' undeclared (first use in this function)
> > | 226 | __kasan_slab_free_mempool(ptr, _RET_IP_);
> > | | ^~~~~~~~
> > | ./include/linux/kasan.h: In function 'kasan_check_byte':
> > | ./include/linux/kasan.h:277:35: error: '_RET_IP_' undeclared (first use in this function)
> > | 277 | return __kasan_check_byte(addr, _RET_IP_);
> > | | ^~~~~~~~
> >
> > Fix this by including <linux/kernel.h> explicitly.
>
> Hi Mark,
>
> Marco already sent a fix for this. It should be in the mm tree.
> (Although the link to it in the Andrew's notification email doesn't
> work. But they rarely do :)
>
> > As a heads-up, there are some unrelated runtime issues with
> > CONFIG_KASAN_HW_TAGS and the recent arm64 string routines rework, which
> > I'm looking into now. If you boot-test with this applied, you should
> > expect to see those.
>
> +Sam, +Robin
>
> Looks like the new strlen routine is making accesses past the allocated buffer.
>
> The guilty commit is 325a1de81287 ("arm64: Import updated version of
> Cortex Strings' strlen").

FWIW, I already have a fix for this, I'm just cleaning it up and will
post shortly.

The issue is that the new strlen() will make unaligned 16-byte accesses
within a naturally-aligned 4096-byte window and over-read by up to 15
bytes; we can fiddle with its alignment fixup to always align to 16
bytes when MTE is in use so any over-read is within the same MTE granule
as the final byte of the string.

I've checked the other routines, and AFAICT they never make accesses
which staddle a 16-byte boundary.

Thanks,
Mark.

2021-07-12 10:59:58

by Will Deacon

[permalink] [raw]

Subject: Re: [PATCH] kasan: fix build for CONFIG_KASAN_HW_TAGS

2021-07-12 11:01:24

by Marco Elver

[permalink] [raw]

Subject: Re: [PATCH] kasan: fix build for CONFIG_KASAN_HW_TAGS

On Mon, 12 Jul 2021 at 11:58, Will Deacon <[email protected]> wrote:
> On Sat, Jul 10, 2021 at 09:16:14PM +0200, Andrey Konovalov wrote:
> > On Thu, Jul 8, 2021 at 4:44 PM Mark Rutland <[email protected]> wrote:
> > >
> > > When CONFIG_KASAN_HW_TAGS is selected, <linux/kasan.h> uses _RET_IP_,
> > > but doesn't explicitly include <linux/kernel.h> where this is defined.
> > >
> > > We used to get this via a transitive include, but since commit:
> > >
> > > f39650de687e3576 ("kernel.h: split out panic and oops helpers")
> > >
> > > ... this is no longer the case, and so we get a build failure:
> > >
> > > | CC arch/arm64/mm/kasan_init.o
> > > | In file included from arch/arm64/mm/kasan_init.c:10:
> > > | ./include/linux/kasan.h: In function 'kasan_slab_free':
> > > | ./include/linux/kasan.h:211:39: error: '_RET_IP_' undeclared (first use in this function)
> > > | 211 | return __kasan_slab_free(s, object, _RET_IP_, init);
> > > | | ^~~~~~~~
> > > | ./include/linux/kasan.h:211:39: note: each undeclared identifier is reported only once for each function it appears in
> > > | ./include/linux/kasan.h: In function 'kasan_kfree_large':
> > > | ./include/linux/kasan.h:219:28: error: '_RET_IP_' undeclared (first use in this function)
> > > | 219 | __kasan_kfree_large(ptr, _RET_IP_);
> > > | | ^~~~~~~~
> > > | ./include/linux/kasan.h: In function 'kasan_slab_free_mempool':
> > > | ./include/linux/kasan.h:226:34: error: '_RET_IP_' undeclared (first use in this function)
> > > | 226 | __kasan_slab_free_mempool(ptr, _RET_IP_);
> > > | | ^~~~~~~~
> > > | ./include/linux/kasan.h: In function 'kasan_check_byte':
> > > | ./include/linux/kasan.h:277:35: error: '_RET_IP_' undeclared (first use in this function)
> > > | 277 | return __kasan_check_byte(addr, _RET_IP_);
> > > | | ^~~~~~~~
> > >
> > > Fix this by including <linux/kernel.h> explicitly.
> >
> > Hi Mark,
> >
> > Marco already sent a fix for this. It should be in the mm tree.
> > (Although the link to it in the Andrew's notification email doesn't
> > work. But they rarely do :)
>
> Do you have a link to the patch? I couldn't spot it in linux-next.

https://lkml.kernel.org/r/[email protected]
( https://lore.kernel.org/mm-commits/20210706204723.O1wZ2%[email protected]/
)

Looks like latest -mm is not yet reflected in -next.