From: Oleg Nesterov <oleg@redhat.com>
To: Alan Stern <stern@rowland.harvard.edu>,
Arnaldo Carvalho de Melo <acme@redhat.com>,
Frederic Weisbecker <fweisbec@gmail.com>,
Ingo Molnar <mingo@elte.hu>, Paul Mackerras <paulus@samba.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Prasad <prasad@linux.vnet.ibm.com>,
Roland McGrath <roland@redhat.com>
Cc: linux-kernel@vger.kernel.org
Subject: Q: perf_event && task->ptrace_bps[]
Date: Mon, 8 Nov 2010 15:56:47 +0100 [thread overview]
Message-ID: <20101108145647.GA3426@redhat.com> (raw)
Hello.
I am trying to understand the usage of hw-breakpoints in arch_ptrace().
ptrace_set_debugreg() and related code looks obviously racy. Nothing
protects us against flush_ptrace_hw_breakpoint() called by the dying
tracee. Afaics we can leak perf_event or use the already freed memory
or both.
Am I missed something?
Looking into the git history, I don't even know which patch should be
blamed (if I am right), there were too many changes. I noticed that
2ebd4ffb6d0cb877787b1e42be8485820158857e "perf events: Split out task
search into helper" moved the PF_EXITING check from find_get_context().
This check coould help if sys_ptrace() races with SIGKILL, but it was
racy anyway.
It is not clear to me what should be done. Looking more, I do not
understand the scope of perf_event/ctx at all, sys_perf_event_open()
looks wrong too, see the next email I am going to send.
Oleg.
next reply other threads:[~2010-11-08 15:03 UTC|newest]
Thread overview: 91+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-08 14:56 Oleg Nesterov [this message]
2010-11-08 14:57 ` Q: sys_perf_event_open() && PF_EXITING Oleg Nesterov
2011-01-19 18:21 ` [PATCH 0/2] Was: " Oleg Nesterov
2011-01-19 18:22 ` [PATCH 1/2] perf: fix find_get_context() vs perf_event_exit_task() race Oleg Nesterov
2011-01-19 18:49 ` Peter Zijlstra
2011-01-19 19:18 ` [tip:perf/urgent] perf: Fix " tip-bot for Oleg Nesterov
2011-01-21 15:29 ` Ingo Molnar
2011-01-21 15:53 ` Oleg Nesterov
2011-01-21 17:45 ` [PATCH] perf: perf_event_exit_task_context: s/rcu_dereference/rcu_dereference_raw/ Oleg Nesterov
2011-01-21 17:53 ` Oleg Nesterov
2011-01-21 21:50 ` Paul E. McKenney
2011-01-24 11:51 ` Oleg Nesterov
2011-01-21 22:12 ` [tip:perf/urgent] " tip-bot for Oleg Nesterov
2011-01-19 18:22 ` [PATCH 2/2] perf: fix perf_event_init_task()/perf_event_free_task() interaction Oleg Nesterov
2011-01-19 18:51 ` Peter Zijlstra
2011-01-19 19:19 ` [tip:perf/urgent] perf: Fix " tip-bot for Oleg Nesterov
2011-01-20 19:30 ` Q: perf_install_in_context/perf_event_enable are racy? Oleg Nesterov
2011-01-21 12:11 ` Peter Zijlstra
2011-01-21 13:03 ` Ingo Molnar
2011-01-21 13:39 ` Peter Zijlstra
2011-01-21 14:26 ` Oleg Nesterov
2011-01-21 15:05 ` Peter Zijlstra
2011-01-21 20:40 ` Frederic Weisbecker
2011-01-24 11:42 ` Oleg Nesterov
2011-01-26 17:53 ` Oleg Nesterov
2011-01-26 18:49 ` Oleg Nesterov
2011-01-26 18:51 ` [PATCH] fix the theoretical task_cpu/task_curr problem in kick_process/task_oncpu_function_call Oleg Nesterov
2011-01-26 19:05 ` Q: perf_install_in_context/perf_event_enable are racy? Peter Zijlstra
2011-01-26 19:33 ` Peter Zijlstra
2011-01-26 19:38 ` Peter Zijlstra
2011-01-26 21:19 ` Oleg Nesterov
2011-01-26 21:33 ` Oleg Nesterov
2011-01-27 10:32 ` Peter Zijlstra
2011-01-27 12:29 ` Peter Zijlstra
2011-01-27 16:10 ` Oleg Nesterov
2011-01-27 16:27 ` Peter Zijlstra
2011-01-27 16:59 ` Oleg Nesterov
2011-01-27 15:52 ` Oleg Nesterov
2011-01-27 13:14 ` Peter Zijlstra
2011-01-27 14:28 ` Peter Zijlstra
2011-01-27 14:58 ` Peter Zijlstra
2011-01-27 16:57 ` Oleg Nesterov
2011-01-27 17:11 ` Peter Zijlstra
2011-01-27 22:18 ` Oleg Nesterov
2011-01-28 11:52 ` Peter Zijlstra
2011-01-28 14:57 ` Peter Zijlstra
2011-01-28 16:28 ` Oleg Nesterov
2011-01-28 18:11 ` Peter Zijlstra
2011-01-31 17:26 ` Oleg Nesterov
2011-01-31 18:23 ` Peter Zijlstra
2011-01-31 19:11 ` Oleg Nesterov
2011-01-31 19:29 ` Peter Zijlstra
2011-02-01 14:03 ` [PATCH] perf: Cure task_oncpu_function_call() races Peter Zijlstra
2011-02-01 17:27 ` Oleg Nesterov
2011-02-01 18:08 ` Peter Zijlstra
2011-02-01 18:18 ` Peter Zijlstra
2011-02-01 21:00 ` Peter Zijlstra
2010-11-08 14:57 ` Q: perf_event && event->owner Oleg Nesterov
2010-11-08 20:11 ` Frederic Weisbecker
2010-11-08 20:41 ` Peter Zijlstra
2010-11-09 16:18 ` Oleg Nesterov
2010-11-09 15:57 ` Oleg Nesterov
2010-11-09 16:56 ` Peter Zijlstra
2010-11-09 16:58 ` Oleg Nesterov
2010-11-09 17:07 ` Peter Zijlstra
2010-11-09 17:42 ` Oleg Nesterov
2010-11-09 18:01 ` Peter Zijlstra
2010-11-09 18:57 ` Oleg Nesterov
2010-11-09 19:16 ` Peter Zijlstra
2010-11-10 15:17 ` Peter Zijlstra
2010-11-10 15:44 ` Oleg Nesterov
2010-11-12 15:48 ` Peter Zijlstra
2010-11-12 18:49 ` Oleg Nesterov
2010-11-18 14:09 ` [tip:perf/urgent] perf: Fix owner-list vs exit tip-bot for Peter Zijlstra
2010-11-08 18:41 ` Q: perf_event && task->ptrace_bps[] Frederic Weisbecker
2010-11-08 19:18 ` Oleg Nesterov
2011-01-17 23:58 ` Frederic Weisbecker
2011-01-18 1:16 ` Roland McGrath
2011-01-17 20:34 ` Oleg Nesterov
2011-01-17 20:52 ` Peter Zijlstra
2011-01-17 21:01 ` Frederic Weisbecker
2011-01-18 16:09 ` [PATCH 0/2] perf: event->cpu checking fixes Oleg Nesterov
2011-01-18 16:10 ` [PATCH 1/2] perf: find_get_context: fix the per-cpu-counter check Oleg Nesterov
2011-01-18 19:06 ` [tip:perf/urgent] perf: Find_get_context: " tip-bot for Oleg Nesterov
2011-01-18 16:10 ` [PATCH 2/2] perf: validate cpu early in perf_event_alloc() Oleg Nesterov
2011-01-18 19:07 ` [tip:perf/urgent] perf: Validate " tip-bot for Oleg Nesterov
2011-01-18 18:42 ` Q: perf_event && task->ptrace_bps[] Frederic Weisbecker
2011-01-19 15:37 ` Oleg Nesterov
2011-01-19 20:05 ` Frederic Weisbecker
2011-01-20 17:28 ` Oleg Nesterov
2011-01-28 17:41 ` Frederic Weisbecker
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=20101108145647.GA3426@redhat.com \
--to=oleg@redhat.com \
--cc=a.p.zijlstra@chello.nl \
--cc=acme@redhat.com \
--cc=fweisbec@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@elte.hu \
--cc=paulus@samba.org \
--cc=prasad@linux.vnet.ibm.com \
--cc=roland@redhat.com \
--cc=stern@rowland.harvard.edu \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.