[PATCHv2] lib/test_kasan: add roundtrip tests

Message ID 20190819161449.30248-1-mark.rutland@arm.com
State Superseded
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Series
  • [PATCHv2] lib/test_kasan: add roundtrip tests
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Commit Message

Mark Rutland Aug. 19, 2019, 4:14 p.m.
In several places we need to be able to operate on pointers which have
gone via a roundtrip:

	virt -> {phys,page} -> virt

With KASAN_SW_TAGS, we can't preserve the tag for SLUB objects, and the
{phys,page} -> virt conversion will use KASAN_TAG_KERNEL.

This patch adds tests to ensure that this works as expected, without
false positives which have recently been spotted [1,2] in testing.

[1] https://lore.kernel.org/linux-arm-kernel/20190819114420.2535-1-walter-zh.wu@mediatek.com/
[2] https://lore.kernel.org/linux-arm-kernel/20190819132347.GB9927@lakrids.cambridge.arm.com/

Signed-off-by: Mark Rutland <mark.rutland@arm.com>

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

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

Cc: Alexander Potapenko <glider@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Will Deacon <will.deacon@arm.com>
---
 lib/test_kasan.c | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

Since v1:
* Spin as a separate patch
* Fix typo
* Note examples in commit message.

Mark.

-- 
2.11.0

Comments

Andrey Ryabinin Aug. 19, 2019, 5:25 p.m. | #1
On 8/19/19 7:14 PM, Mark Rutland wrote:
> In several places we need to be able to operate on pointers which have

> gone via a roundtrip:

> 

> 	virt -> {phys,page} -> virt

> 

> With KASAN_SW_TAGS, we can't preserve the tag for SLUB objects, and the

> {phys,page} -> virt conversion will use KASAN_TAG_KERNEL.

> 

> This patch adds tests to ensure that this works as expected, without

> false positives which have recently been spotted [1,2] in testing.

> 

> [1] https://lore.kernel.org/linux-arm-kernel/20190819114420.2535-1-walter-zh.wu@mediatek.com/

> [2] https://lore.kernel.org/linux-arm-kernel/20190819132347.GB9927@lakrids.cambridge.arm.com/

> 

> Signed-off-by: Mark Rutland <mark.rutland@arm.com>

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

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

> Cc: Alexander Potapenko <glider@google.com>

> Cc: Andrew Morton <akpm@linux-foundation.org>

> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>

> Cc: Dmitry Vyukov <dvyukov@google.com>

> Cc: Will Deacon <will.deacon@arm.com>

> ---



Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Andrew Morton Aug. 22, 2019, 11:48 p.m. | #2
On Mon, 19 Aug 2019 17:14:49 +0100 Mark Rutland <mark.rutland@arm.com> wrote:

> In several places we need to be able to operate on pointers which have

> gone via a roundtrip:

> 

> 	virt -> {phys,page} -> virt

> 

> With KASAN_SW_TAGS, we can't preserve the tag for SLUB objects, and the

> {phys,page} -> virt conversion will use KASAN_TAG_KERNEL.

> 

> This patch adds tests to ensure that this works as expected, without

> false positives which have recently been spotted [1,2] in testing.

> 

> [1] https://lore.kernel.org/linux-arm-kernel/20190819114420.2535-1-walter-zh.wu@mediatek.com/

> [2] https://lore.kernel.org/linux-arm-kernel/20190819132347.GB9927@lakrids.cambridge.arm.com/

> 

>

> ...

>


The only change I'm seeing from v1 is:

--- a/lib/test_kasan.c~lib-test_kasan-add-roundtrip-tests-v2
+++ a/lib/test_kasan.c
@@ -19,7 +19,6 @@
 #include <linux/string.h>
 #include <linux/uaccess.h>
 
-#include <asm/io.h>
 #include <asm/page.h>
 
 /*

which is really kinda wrong.  We should strictly include linux/io.h for
things like virt_to_phys().

So I think I'll stick with v1 plus my fixlet:

--- a/lib/test_kasan.c~lib-test_kasan-add-roundtrip-tests-checkpatch-fixes
+++ a/lib/test_kasan.c
@@ -18,8 +18,8 @@
 #include <linux/slab.h>
 #include <linux/string.h>
 #include <linux/uaccess.h>
+#include <linux/io.h>
 
-#include <asm/io.h>
 #include <asm/page.h>
 
 /*

> Since v1:

> * Spin as a separate patch

> * Fix typo

> * Note examples in commit message.


So I'm not sure what happened to these things.  Did you send the correct
patch?
Mark Rutland Aug. 23, 2019, 10:41 a.m. | #3
Hi Andrew,

On Thu, Aug 22, 2019 at 04:48:57PM -0700, Andrew Morton wrote:
> On Mon, 19 Aug 2019 17:14:49 +0100 Mark Rutland <mark.rutland@arm.com> wrote:

> 

> > In several places we need to be able to operate on pointers which have

> > gone via a roundtrip:

> > 

> > 	virt -> {phys,page} -> virt

> > 

> > With KASAN_SW_TAGS, we can't preserve the tag for SLUB objects, and the

> > {phys,page} -> virt conversion will use KASAN_TAG_KERNEL.

> > 

> > This patch adds tests to ensure that this works as expected, without

> > false positives which have recently been spotted [1,2] in testing.

> > 

> > [1] https://lore.kernel.org/linux-arm-kernel/20190819114420.2535-1-walter-zh.wu@mediatek.com/

> > [2] https://lore.kernel.org/linux-arm-kernel/20190819132347.GB9927@lakrids.cambridge.arm.com/

> > 

> >

> > ...

> >

> 

> The only change I'm seeing from v1 is:

> 

> --- a/lib/test_kasan.c~lib-test_kasan-add-roundtrip-tests-v2

> +++ a/lib/test_kasan.c

> @@ -19,7 +19,6 @@

>  #include <linux/string.h>

>  #include <linux/uaccess.h>

>  

> -#include <asm/io.h>

>  #include <asm/page.h>


I think you've confused v1 with v3 (which was the first version to
include <asm/io.h>).

v1: https://lore.kernel.org/linux-arm-kernel/20190819150341.GC9927@lakrids.cambridge.arm.com/
v3: https://lore.kernel.org/linux-arm-kernel/20190819150341.GC9927@lakrids.cambridge.arm.com/

I guess as v1 was part of a reply (without the mail subject matching)
that might have confused things? Sorry about that if so!

>  

>  /*

> 

> which is really kinda wrong.  We should strictly include linux/io.h for

> things like virt_to_phys().

> 

> So I think I'll stick with v1 plus my fixlet:

> 

> --- a/lib/test_kasan.c~lib-test_kasan-add-roundtrip-tests-checkpatch-fixes

> +++ a/lib/test_kasan.c

> @@ -18,8 +18,8 @@

>  #include <linux/slab.h>

>  #include <linux/string.h>

>  #include <linux/uaccess.h>

> +#include <linux/io.h>

>  

> -#include <asm/io.h>

>  #include <asm/page.h>

>  

>  /*

> 


Assuming that you mean *v3* with that fix, that looks good to me!

Thanks,
Mark.
Andrew Morton Aug. 24, 2019, 8:30 p.m. | #4
On Fri, 23 Aug 2019 11:41:08 +0100 Mark Rutland <mark.rutland@arm.com> wrote:

> >  

> >  /*

> > 

> > which is really kinda wrong.  We should strictly include linux/io.h for

> > things like virt_to_phys().

> > 

> > So I think I'll stick with v1 plus my fixlet:

> > 

> > --- a/lib/test_kasan.c~lib-test_kasan-add-roundtrip-tests-checkpatch-fixes

> > +++ a/lib/test_kasan.c

> > @@ -18,8 +18,8 @@

> >  #include <linux/slab.h>

> >  #include <linux/string.h>

> >  #include <linux/uaccess.h>

> > +#include <linux/io.h>

> >  

> > -#include <asm/io.h>

> >  #include <asm/page.h>

> >  

> >  /*

> > 

> 

> Assuming that you mean *v3* with that fix, that looks good to me!


Yes, that's what we have.

Patch

diff --git a/lib/test_kasan.c b/lib/test_kasan.c
index b63b367a94e8..cf7b93f0d90c 100644
--- a/lib/test_kasan.c
+++ b/lib/test_kasan.c
@@ -19,6 +19,8 @@ 
 #include <linux/string.h>
 #include <linux/uaccess.h>
 
+#include <asm/page.h>
+
 /*
  * Note: test functions are marked noinline so that their names appear in
  * reports.
@@ -337,6 +339,42 @@  static noinline void __init kmalloc_uaf2(void)
 	kfree(ptr2);
 }
 
+static noinline void __init kfree_via_page(void)
+{
+	char *ptr;
+	size_t size = 8;
+	struct page *page;
+	unsigned long offset;
+
+	pr_info("invalid-free false positive (via page)\n");
+	ptr = kmalloc(size, GFP_KERNEL);
+	if (!ptr) {
+		pr_err("Allocation failed\n");
+		return;
+	}
+
+	page = virt_to_page(ptr);
+	offset = offset_in_page(ptr);
+	kfree(page_address(page) + offset);
+}
+
+static noinline void __init kfree_via_phys(void)
+{
+	char *ptr;
+	size_t size = 8;
+	phys_addr_t phys;
+
+	pr_info("invalid-free false positive (via phys)\n");
+	ptr = kmalloc(size, GFP_KERNEL);
+	if (!ptr) {
+		pr_err("Allocation failed\n");
+		return;
+	}
+
+	phys = virt_to_phys(ptr);
+	kfree(phys_to_virt(phys));
+}
+
 static noinline void __init kmem_cache_oob(void)
 {
 	char *p;
@@ -737,6 +775,8 @@  static int __init kmalloc_tests_init(void)
 	kmalloc_uaf();
 	kmalloc_uaf_memset();
 	kmalloc_uaf2();
+	kfree_via_page();
+	kfree_via_phys();
 	kmem_cache_oob();
 	memcg_accounted_kmem_cache();
 	kasan_stack_oob();