From: Walter Wu <walter-zh.wu@mediatek.com>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: 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>, <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: Fri, 6 Sep 2019 11:15:34 +0800 [thread overview]
Message-ID: <1567739734.32522.67.camel@mtksdccf07> (raw)
In-Reply-To: <99913463-0e2c-7dab-c1eb-8b9e149b3ee3@suse.cz>
On Thu, 2019-09-05 at 10:03 +0200, Vlastimil Babka wrote:
> On 9/4/19 4:24 PM, Walter Wu wrote:
> > On Wed, 2019-09-04 at 16:13 +0200, Vlastimil Babka wrote:
> >> On 9/4/19 4:06 PM, Walter Wu wrote:
> >>
> >> The THP fix is not required for the rest of the series, it was even merged to
> >> mainline separately.
> >>
> >>> And It looks like something is different, because we only need last
> >>> stack of page, so it can decrease memory overhead.
> >>
> >> That would save you depot_stack_handle_t (which is u32) per page. I guess that's
> >> nothing compared to KASAN overhead?
> >>
> > If we can use less memory, we can achieve what we want. Why not?
>
> In my experience to solve some UAFs, it's important to know not only the
> freeing stack, but also the allocating stack. Do they make sense together,
> or not? In some cases, even longer history of alloc/free would be nice :)
>
We think it only has free stack to find out the root cause. Maybe we can
refer to other people's experience and ideas.
> Also by simply recording the free stack in the existing depot handle,
> you might confuse existing page_owner file consumers, who won't know
> that this is a freeing stack.
>
Don't worry it.
1. Our feature option has this description about last stack of page.
when consumer enable our feature, they should know the changing.
2. We add to print text message for alloc or free stack before dump the
stack of page. so consumers should know what is it.
> All that just doesn't seem to justify saving an u32 per page.
Actually, We want to slim memory usage instead of increasing the memory
usage at another mail discussion. Maybe, maintainer or reviewer can
provide some ideas. That will be great.
> >
> >
>
next prev parent reply other threads:[~2019-09-06 3:15 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
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 [this message]
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1567739734.32522.67.camel@mtksdccf07 \
--to=walter-zh.wu@mediatek.com \
--cc=akpm@linux-foundation.org \
--cc=arnd@arndb.de \
--cc=aryabinin@virtuozzo.com \
--cc=dvyukov@google.com \
--cc=glider@google.com \
--cc=kasan-dev@googlegroups.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mediatek@lists.infradead.org \
--cc=linux-mm@kvack.org \
--cc=matthias.bgg@gmail.com \
--cc=schwidefsky@de.ibm.com \
--cc=vbabka@suse.cz \
--cc=wsd_upstream@mediatek.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).