From: Kenji Arisawa <arisawa@ar.aichi-u.ac.jp>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
Subject: Re: [9fans] dns
Date: Sat, 25 Aug 2012 21:37:05 +0900 [thread overview]
Message-ID: <CB0F953E-5837-4DEB-9C48-62EC246059A4@ar.aichi-u.ac.jp> (raw)
In-Reply-To: <7e82960b744e04ccfb76f7a0f3161b94@rei2.9hal>
Hello cinap,
broken dns triggers Fauth problem, so I have rebooted.
I will get snapshot at next crash.
Kenji Arisawa
On 2012/08/25, at 19:54, cinap_lenrek@gmx.de wrote:
> always make a process snapshot as the kernel might discard
> your broken process once it runs low on memory so you have
> time to debug:
>
> snap 41356 >/tmp/dns.snap
>
> char *domain strings alloc header seems to have been corrupted
> (or just freed by accident?).
>
> the string just gets allocated and freed in mydnsquery() so its
> unlikely a bug there. someone else has corrupted its alloc header?
>
> it looks more like corruption as we dont hand this pointer out to
> someone else but netmkaddr().
>
> look at the raw data, often one can get a clue by what it got
> overridden with and try to figure out what the previous block
> before our block that got corrupted was. the pool allocator keeps
> the callerpc's of who allocated the block so you can use that
> to figure out what it is, or look at the contents.
>
> // dump the memory arround our corrupted block
> dump(0x497f8 - 0x10, 0x100, "X")
>
> maybe our block didnt got overridden but really freed with
> a call to free but with the wrong pointer? check the alloc
> magic!
>
> // check the contents, should be an ip address string
> dump(0x49800, 1, "s")
>
> run acid with -lpool -lleak and run blockdump() if its
> corrupted block, it might just stop at the block before
> our one and will print the allocpc's and give some
> diagnostics.
>
> i can try this if you provide process snapshot file.
>
> --
> cinap
>
next prev parent reply other threads:[~2012-08-25 12:37 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-21 1:51 Jeff Sickel
2012-08-21 1:59 ` erik quanstrom
2012-08-21 4:23 ` arisawa
2012-08-21 5:08 ` Jeff Sickel
2012-08-21 8:42 ` Kenji Arisawa
2012-08-21 11:27 ` cinap_lenrek
2012-08-21 12:18 ` Lucio De Re
2012-08-21 12:37 ` arisawa
2012-08-21 18:32 ` erik quanstrom
2012-08-21 20:05 ` Charles Forsyth
[not found] ` <CAOw7k5hALBex13jJUbscVt4th-Z9urpmAP0eOBi7b1HuBQESrw@mail.gmail.c>
2012-08-21 20:41 ` erik quanstrom
2012-08-21 22:44 ` cinap_lenrek
2012-08-22 10:32 ` cinap_lenrek
2012-08-22 12:09 ` Kenji Arisawa
2012-08-22 12:35 ` cinap_lenrek
2012-08-22 13:05 ` erik quanstrom
2012-08-22 13:08 ` erik quanstrom
2012-08-22 13:11 ` Charles Forsyth
[not found] ` <CAOw7k5gGhL-=E=V1C9ffQP7qMyUVMhtrgpzLMidnCsHFGDzHwA@mail.gmail.c>
2012-08-22 13:18 ` erik quanstrom
2012-08-22 13:21 ` Charles Forsyth
2012-08-22 13:31 ` cinap_lenrek
2012-08-22 14:22 ` erik quanstrom
2012-08-22 14:41 ` Charles Forsyth
2012-08-22 14:47 ` cinap_lenrek
2012-08-22 15:26 ` erik quanstrom
2012-08-22 15:33 ` erik quanstrom
2012-08-22 15:35 ` erik quanstrom
[not found] ` <CAOw7k5jOE0Bf13fXJ04dUF4vGniRTJ1LwEMV1Oqw=AFKg77boA@mail.gmail.com>
2012-08-22 16:05 ` Charles Forsyth
2012-08-22 13:23 ` Lucio De Re
2012-08-25 0:10 ` Kenji Arisawa
2012-08-25 10:54 ` cinap_lenrek
2012-08-25 12:37 ` Kenji Arisawa [this message]
2012-08-25 13:22 ` cinap_lenrek
2012-08-25 13:38 ` cinap_lenrek
2012-08-25 13:41 ` Charles Forsyth
2012-08-25 13:44 ` cinap_lenrek
2012-08-27 22:44 ` arisawa
2012-08-28 1:45 ` cinap_lenrek
2012-08-28 1:57 ` erik quanstrom
2012-08-28 2:08 ` cinap_lenrek
2012-08-28 4:03 ` erik quanstrom
2012-09-08 17:37 ` Skip Tavakkolian
2012-09-08 18:02 ` cinap_lenrek
2012-09-08 18:18 ` cinap_lenrek
2012-09-08 21:53 ` Skip Tavakkolian
2012-09-08 22:27 ` cinap_lenrek
2012-09-09 2:09 ` Charles Forsyth
2012-09-09 2:37 ` cinap_lenrek
2012-09-09 3:01 ` Charles Forsyth
[not found] ` <CAOw7k5jydN7wssxBEqTc6h9FtLErjkoyxyfuQZLgcBTZ-nRgiw@mail.gmail.c>
2012-09-09 4:26 ` erik quanstrom
2012-09-09 5:28 ` Skip Tavakkolian
2012-08-25 21:56 ` cinap_lenrek
2012-08-26 13:16 ` cinap_lenrek
2012-08-26 13:36 ` Charles Forsyth
2012-08-21 5:08 ` Benjamin Huntsman
-- strict thread matches above, loose matches on Subject: below --
2017-04-01 1:28 [9fans] DNS cinap_lenrek
2017-04-01 3:40 ` Skip Tavakkolian
2017-04-01 9:46 ` Alexandru Gheorghe
2017-04-01 17:04 ` Steve Simon
2017-04-03 7:06 ` David Arroyo
2017-03-20 7:26 Skip Tavakkolian
2017-03-21 19:19 ` Skip Tavakkolian
2017-03-30 22:19 ` Steve Simon
2017-03-31 7:43 ` Peter Hull
2012-08-26 14:48 [9fans] dns cinap_lenrek
2007-08-15 19:26 erik quanstrom
2007-07-03 20:54 erik quanstrom
2007-07-04 20:51 ` geoff
2007-07-04 21:18 ` erik quanstrom
2007-07-04 21:52 ` geoff
2004-03-20 2:25 David Presotto
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