From: Vlastimil Babka <vbabka@suse.cz>
To: Walter Wu <walter-zh.wu@mediatek.com>,
Andrey Ryabinin <aryabinin@virtuozzo.com>,
Alexander Potapenko <glider@google.com>,
Dmitry Vyukov <dvyukov@google.com>,
Matthias Brugger <matthias.bgg@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
Arnd Bergmann <arnd@arndb.de>
Cc: kasan-dev@googlegroups.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-mediatek@lists.infradead.org, wsd_upstream@mediatek.com
Subject: Re: [PATCH 1/2] mm/kasan: dump alloc/free stack for page allocator
Date: Wed, 4 Sep 2019 14:49:06 +0200 [thread overview]
Message-ID: <401064ae-279d-bef3-a8d5-0fe155d0886d@suse.cz> (raw)
In-Reply-To: <20190904065133.20268-1-walter-zh.wu@mediatek.com>
On 9/4/19 8:51 AM, Walter Wu wrote:
> This patch is KASAN report adds the alloc/free stacks for page allocator
> in order to help programmer to see memory corruption caused by page.
>
> By default, KASAN doesn't record alloc/free stack for page allocator.
> It is difficult to fix up page use-after-free issue.
>
> This feature depends on page owner to record the last stack of pages.
> It is very helpful for solving the page use-after-free or out-of-bound.
>
> KASAN report will show the last stack of page, it may be:
> a) If page is in-use state, then it prints alloc stack.
> It is useful to fix up page out-of-bound issue.
I expect this will conflict both in syntax and semantics with my series [1] that
adds the freeing stack to page_owner when used together with debug_pagealloc,
and it's now in mmotm. Glad others see the need as well :) Perhaps you could
review the series, see if it fulfils your usecase (AFAICS the series should be a
superset, by storing both stacks at once), and perhaps either make KASAN enable
debug_pagealloc, or turn KASAN into an alternative enabler of the functionality
there?
Thanks, Vlastimil
[1] https://lore.kernel.org/linux-mm/20190820131828.22684-1-vbabka@suse.cz/t/#u
> BUG: KASAN: slab-out-of-bounds in kmalloc_pagealloc_oob_right+0x88/0x90
> Write of size 1 at addr ffffffc0d64ea00a by task cat/115
> ...
> Allocation stack of page:
> prep_new_page+0x1a0/0x1d8
> get_page_from_freelist+0xd78/0x2748
> __alloc_pages_nodemask+0x1d4/0x1978
> kmalloc_order+0x28/0x58
> kmalloc_order_trace+0x28/0xe0
> kmalloc_pagealloc_oob_right+0x2c/0x90
>
> b) If page is freed state, then it prints free stack.
> It is useful to fix up page use-after-free issue.
>
> BUG: KASAN: use-after-free in kmalloc_pagealloc_uaf+0x70/0x80
> Write of size 1 at addr ffffffc0d651c000 by task cat/115
> ...
> Free stack of page:
> kasan_free_pages+0x68/0x70
> __free_pages_ok+0x3c0/0x1328
> __free_pages+0x50/0x78
> kfree+0x1c4/0x250
> kmalloc_pagealloc_uaf+0x38/0x80
>
>
> This has been discussed, please refer below link.
> https://bugzilla.kernel.org/show_bug.cgi?id=203967
>
> Signed-off-by: Walter Wu <walter-zh.wu@mediatek.com>
> ---
> lib/Kconfig.kasan | 9 +++++++++
> mm/kasan/common.c | 6 ++++++
> 2 files changed, 15 insertions(+)
>
> diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
> index 4fafba1a923b..ba17f706b5f8 100644
> --- a/lib/Kconfig.kasan
> +++ b/lib/Kconfig.kasan
> @@ -135,6 +135,15 @@ config KASAN_S390_4_LEVEL_PAGING
> to 3TB of RAM with KASan enabled). This options allows to force
> 4-level paging instead.
>
> +config KASAN_DUMP_PAGE
> + bool "Dump the page last stack information"
> + depends on KASAN && PAGE_OWNER
> + help
> + By default, KASAN doesn't record alloc/free stack for page allocator.
> + It is difficult to fix up page use-after-free issue.
> + This feature depends on page owner to record the last stack of page.
> + It is very helpful for solving the page use-after-free or out-of-bound.
> +
> config TEST_KASAN
> tristate "Module for testing KASAN for bug detection"
> depends on m && KASAN
> diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> index 2277b82902d8..2a32474efa74 100644
> --- a/mm/kasan/common.c
> +++ b/mm/kasan/common.c
> @@ -35,6 +35,7 @@
> #include <linux/vmalloc.h>
> #include <linux/bug.h>
> #include <linux/uaccess.h>
> +#include <linux/page_owner.h>
>
> #include "kasan.h"
> #include "../slab.h"
> @@ -227,6 +228,11 @@ void kasan_alloc_pages(struct page *page, unsigned int order)
>
> void kasan_free_pages(struct page *page, unsigned int order)
> {
> +#ifdef CONFIG_KASAN_DUMP_PAGE
> + gfp_t gfp_flags = GFP_KERNEL;
> +
> + set_page_owner(page, order, gfp_flags);
> +#endif
> if (likely(!PageHighMem(page)))
> kasan_poison_shadow(page_address(page),
> PAGE_SIZE << order,
>
next prev parent reply other threads:[~2019-09-04 12:49 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-04 6:51 [PATCH 1/2] mm/kasan: dump alloc/free stack for page allocator Walter Wu
2019-09-04 12:49 ` Vlastimil Babka [this message]
2019-09-04 14:06 ` Walter Wu
2019-09-04 14:13 ` Vlastimil Babka
2019-09-04 14:24 ` Walter Wu
2019-09-05 8:03 ` Vlastimil Babka
2019-09-06 3:15 ` Walter Wu
2019-09-04 13:44 ` Andrey Konovalov
2019-09-04 14:16 ` Walter Wu
2019-09-04 14:37 ` Qian Cai
2019-09-05 1:54 ` Walter Wu
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