From: Fengnan Chang <changfengnan@bytedance.com>
To: Dmitry Kozlyuk <dmitry.kozliuk@gmail.com>
Cc: anatoly.burakov@intel.com, dev@dpdk.org, xuemingl@mellanox.com
Subject: Re: [External] Re: [PATCH] eal: fix modify data area after memset
Date: Mon, 23 Oct 2023 17:07:21 +0800 [thread overview]
Message-ID: <CAPFOzZuX--9p-dO69C7DiL=R8Z=iU3mg3Jn31LXPHRxt8O9gvQ@mail.gmail.com> (raw)
In-Reply-To: <20231022232234.42168129@sovereign>
[-- Attachment #1: Type: text/plain, Size: 1549 bytes --]
Dmitry Kozlyuk <dmitry.kozliuk@gmail.com> 于2023年10月23日周一 04:22写道：
>
> 2023-09-22 16:12 (UTC+0800), Fengnan Chang:
> > ping
> >
> > Fengnan Chang <changfengnan@bytedance.com> 于2023年9月12日周二 17:05写道：
> > >
> > > Let's look at this path:
> > > malloc_elem_free
> > > ->malloc_elem_join_adjacent_free
> > > ->join_elem(elem, elem->next)
> > >
> > > 0. cur elem's pad > 0
> > > 1. data area memset in malloc_elem_free first.
> > > 2. next elem is free, try to join cur elem and next.
> > > 3. in join_elem, try to modify inner->size, this address had
> > > memset in step 1, it casue the content of addrees become non-zero.
> > >
> > > If user call rte_zmalloc, and pick this elem, it can't get all
> > > zero'd memory.
>
> malloc_elem_join_adjacent_free() always calls memset() after join_elem(),
> for the next and the previous element respectively.
when try to call join_elem() for the next element in
malloc_elem_join_adjacent_free(),
the memset is try to memset *next* element, but join_elem() is update
*current* element's
content, which shoudn't happen, it's two different element.
> How to reproduce this bug?
when I test this patch,
https://patches.dpdk.org/project/dpdk/patch/20230831111937.60975-1-changfengnan@bytedance.com/
I have a case try to alloc 64/128/192 size object and free with 16 threads,
after every
alloc I'll check wheather all content is 0 or not.
It's not easy to reproduce, you can have a try, it's easier to find
this problem in code level.
[-- Attachment #2: Type: text/html, Size: 2148 bytes --]
next prev parent reply other threads:[~2023-10-23 9:07 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-12 9:04 Fengnan Chang
2023-09-22 8:12 ` Fengnan Chang
2023-10-22 20:22 ` Dmitry Kozlyuk
2023-10-23 9:07 ` Fengnan Chang [this message]
2023-10-25 16:03 ` [External] " Stephen Hemminger
2023-10-30 12:31 ` Fengnan Chang
2023-10-17 13:32 ` Thomas Monjalon
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='CAPFOzZuX--9p-dO69C7DiL=R8Z=iU3mg3Jn31LXPHRxt8O9gvQ@mail.gmail.com' \
--to=changfengnan@bytedance.com \
--cc=anatoly.burakov@intel.com \
--cc=dev@dpdk.org \
--cc=dmitry.kozliuk@gmail.com \
--cc=xuemingl@mellanox.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).