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Message-ID: <CACRpkda3Pe9L14_iyKEfeCx1F3XJSLbz_OVHLxX0Lzy9Gt9t9Q@mail.gmail.com>
Date: Tue, 26 May 2015 15:35:03 +0200
From: Linus Walleij <linus.walleij@...aro.org>
To: Andrey Ryabinin <a.ryabinin@...sung.com>
Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Dmitry Vyukov <dvyukov@...gle.com>,
Alexander Potapenko <glider@...gle.com>,
David Keitel <dkeitel@...eaurora.org>,
Arnd Bergmann <arnd@...db.de>,
Andrew Morton <akpm@...ux-foundation.org>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will.deacon@....com>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>, linux-mm@...ck.org
Subject: Re: [PATCH v2 5/5] arm64: add KASan support
On Fri, May 15, 2015 at 3:59 PM, Andrey Ryabinin <a.ryabinin@...sung.com> wrote:
> This patch adds arch specific code for kernel address sanitizer
> (see Documentation/kasan.txt).
I'm trying to test this on the Juno hardware (39 VA bits).
I get this at boot:
Virtual kernel memory layout:
kasan : 0xffffff8000000000 - 0xffffff9000000000 ( 64 MB)
vmalloc : 0xffffff9000000000 - 0xffffffbdbfff0000 ( 182 GB)
Nice, kasan is shadowing vmem perfectly. Also
shadowing itself it appears, well whatever.
I enable CONFIG_KASAN, CONFIG_KASAN_OUTLINE,
CONFIG_STACKTRACE, CONFIG_SLUB_DEBUG_ON, and
CONFIG_TEST_KASAN.
I patch the test like this because I'm not using any loadable
modules:
diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
index 39f24d6721e5..b3353dbe5f58 100644
--- a/lib/Kconfig.kasan
+++ b/lib/Kconfig.kasan
@@ -45,7 +45,7 @@ endchoice
config TEST_KASAN
tristate "Module for testing kasan for bug detection"
- depends on m && KASAN
+ depends on KASAN
help
This is a test module doing various nasty things like
out of bounds accesses, use after free. It is useful for testing
diff --git a/lib/test_kasan.c b/lib/test_kasan.c
index 098c08eddfab..fb54486eacd6 100644
--- a/lib/test_kasan.c
+++ b/lib/test_kasan.c
@@ -273,5 +273,5 @@ static int __init kmalloc_tests_init(void)
return -EAGAIN;
}
-module_init(kmalloc_tests_init);
+late_initcall(kmalloc_tests_init);
MODULE_LICENSE("GPL");
And then at boot I just get this:
kasan test: kmalloc_oob_right out-of-bounds to right
kasan test: kmalloc_oob_left out-of-bounds to left
kasan test: kmalloc_node_oob_right kmalloc_node(): out-of-bounds to right
kasan test: kmalloc_large_oob_rigth kmalloc large allocation:
out-of-bounds to right
kasan test: kmalloc_oob_krealloc_more out-of-bounds after krealloc more
kasan test: kmalloc_oob_krealloc_less out-of-bounds after krealloc less
kasan test: kmalloc_oob_16 kmalloc out-of-bounds for 16-bytes access
kasan test: kmalloc_oob_in_memset out-of-bounds in memset
kasan test: kmalloc_uaf use-after-free
kasan test: kmalloc_uaf_memset use-after-free in memset
kasan test: kmalloc_uaf2 use-after-free after another kmalloc
kasan test: kmem_cache_oob out-of-bounds in kmem_cache_alloc
kasan test: kasan_stack_oob out-of-bounds on stack
kasan test: kasan_global_oob out-of-bounds global variable
W00t no nice KASan warnings (which is what I expect).
This is my compiler by the way:
$ arm-linux-gnueabihf-gcc --version
arm-linux-gnueabihf-gcc (crosstool-NG linaro-1.13.1-4.9-2014.09 -
Linaro GCC 4.9-2014.09) 4.9.2 20140904 (prerelease)
I did the same exercise on the foundation model (FVP) and I guess
that is what you developed the patch set on because there I got
nice KASan dumps:
Virtual kernel memory layout:
kasan : 0xffffff8000000000 - 0xffffff9000000000 ( 64 MB)
vmalloc : 0xffffff9000000000 - 0xffffffbdbfff0000 ( 182 GB)
(...)
kasan test: kmalloc_oob_right out-of-bounds to right
kasan test: kmalloc_oob_left out-of-bounds to left
kasan test: kmalloc_node_oob_right kmalloc_node(): out-of-bounds to right
=============================================================================
BUG kmalloc-4096 (Tainted: G S ): Redzone overwritten
-----------------------------------------------------------------------------
Disabling lock debugging due to kernel taint
INFO: 0xffffffc0676bc480-0xffffffc0676bc480. First byte 0x0 instead of 0xcc
INFO: Allocated in kmalloc_node_oob_right+0x40/0x8c age=0 cpu=1 pid=1
alloc_debug_processing+0x170/0x17c
__slab_alloc.isra.59.constprop.61+0x354/0x374
kmem_cache_alloc+0x1a4/0x1e0
kmalloc_node_oob_right+0x3c/0x8c
kmalloc_tests_init+0x10/0x4c
do_one_initcall+0x88/0x1a0
kernel_init_freeable+0x16c/0x210
kernel_init+0xc/0xd8
ret_from_fork+0xc/0x50
INFO: Freed in cleanup_uevent_env+0x10/0x18 age=0 cpu=3 pid=724
free_debug_processing+0x214/0x30c
__slab_free+0x2b0/0x3f8
kfree+0x1a4/0x1dc
cleanup_uevent_env+0xc/0x18
call_usermodehelper_freeinfo+0x18/0x30
umh_complete+0x34/0x40
____call_usermodehelper+0x170/0x18c
ret_from_fork+0xc/0x50
INFO: Slab 0xffffffbdc39dae00 objects=7 used=1 fp=0xffffffc0676b9180
flags=0x4081
INFO: Object 0xffffffc0676bb480 @offset=13440 fp=0xffffffc0676b8000
Bytes b4 ffffffc0676bb470: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a
5a 5a ZZZZZZZZZZZZZZZZ
Object ffffffc0676bb480: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
6b kkkkkkkkkkkkkkkk
Object ffffffc0676bb490: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
6b kkkkkkkkkkkkkkkk
Object ffffffc0676bb4a0: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
6b kkkkkkkkkkkkkkkk
Object ffffffc0676bb4b0: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
6b kkkkkkkkkkkkkkkk
(...)
kasan test: kmalloc_large_oob_rigth kmalloc large allocation:
out-of-bounds to right
kasan test: kmalloc_oob_krealloc_more out-of-bounds after krealloc more
kasan test: kmalloc_oob_krealloc_less out-of-bounds after krealloc less
kasan test: kmalloc_oob_16 kmalloc out-of-bounds for 16-bytes access
kasan test: kmalloc_oob_in_memset out-of-bounds in memset
kasan test: kmalloc_uaf use-after-free
kasan test: kmalloc_uaf_memset use-after-free in memset
=============================================================================
BUG kmalloc-64 (Tainted: G S B ): Poison overwritten
-----------------------------------------------------------------------------
INFO: 0xffffffc0666e3c08-0xffffffc0666e3c08. First byte 0x78 instead of 0x6b
INFO: Allocated in kmalloc_uaf+0x40/0x8c age=0 cpu=1 pid=1
alloc_debug_processing+0x170/0x17c
__slab_alloc.isra.59.constprop.61+0x354/0x374
kmem_cache_alloc+0x1a4/0x1e0
kmalloc_uaf+0x3c/0x8c
kmalloc_tests_init+0x28/0x4c
do_one_initcall+0x88/0x1a0
kernel_init_freeable+0x16c/0x210
kernel_init+0xc/0xd8
ret_from_fork+0xc/0x50
INFO: Freed in kmalloc_uaf+0x74/0x8c age=0 cpu=1 pid=1
free_debug_processing+0x214/0x30c
__slab_free+0x2b0/0x3f8
kfree+0x1a4/0x1dc
kmalloc_uaf+0x70/0x8c
kmalloc_tests_init+0x28/0x4c
do_one_initcall+0x88/0x1a0
kernel_init_freeable+0x16c/0x210
kernel_init+0xc/0xd8
ret_from_fork+0xc/0x50
INFO: Slab 0xffffffbdc399b880 objects=18 used=18 fp=0x (null)
flags=0x4080
INFO: Object 0xffffffc0666e3c00 @offset=7168 fp=0xffffffc0666e3a40
Bytes b4 ffffffc0666e3bf0: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a
5a 5a ZZZZZZZZZZZZZZZZ
Object ffffffc0666e3c00: 6b 6b 6b 6b 6b 6b 6b 6b 78 6b 6b 6b 6b 6b 6b
6b kkkkkkkkxkkkkkkk
Object ffffffc0666e3c10: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
6b kkkkkkkkkkkkkkkk
Object ffffffc0666e3c20: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
6b kkkkkkkkkkkkkkkk
Object ffffffc0666e3c30: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
a5 kkkkkkkkkkkkkkk.
Redzone ffffffc0666e3c40: bb bb bb bb bb bb bb bb
........
Padding ffffffc0666e3d80: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a
5a ZZZZZZZZZZZZZZZZ
Padding ffffffc0666e3d90: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a
5a ZZZZZZZZZZZZZZZZ
Padding ffffffc0666e3da0: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a
5a ZZZZZZZZZZZZZZZZ
Padding ffffffc0666e3db0: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a
5a ZZZZZZZZZZZZZZZZ
(...)
So it works nicely on emulated hardware it seems.
I wonder were the problem lies, any hints where to start looking
to fix this?
Yours,
Linus Walleij
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