From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>,
Peter Zijlstra <peterz@infradead.org>,
Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
Anton Arapov <anton@redhat.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 6/7] uprobes: Fix uprobe_copy_insn() race with itself
Date: Sat, 6 Oct 2012 15:22:58 +0530 [thread overview]
Message-ID: <20121006095258.GD9145@linux.vnet.ibm.com> (raw)
In-Reply-To: <20120930194224.GA11347@redhat.com>
* Oleg Nesterov <oleg@redhat.com> [2012-09-30 21:42:24]:
> install_breakpoint() is called under mm->mmap_sem, this protects
> set_swbp() but not uprobe_copy_insn(). Two or more different tasks
> can call install_breakpoint()->uprobe_copy_insn() at the same time,
> this leads to numerous problems if UPROBE_COPY_INSN is not set.
>
> Just for example, the second copy_insn() can corrupt the already
> analyzed/fixuped uprobe->arch.insn and race with handle_swbp().
>
> This patch simply adds uprobe->copy_mutex to serialize this code.
> We could probably reuse ->consumer_rwsem, but this would mean that
> consumer->handler() can not use mm->mmap_sem, not good.
>
> Note: this is another temporary ugly hack until we move this logic
> into uprobe_register().
>
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Given that we copy just for the first install, and register not being a
performance path, Can we use a single mutex instead of a per-uprobe
mutex.
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
next prev parent reply other threads:[~2012-10-06 9:52 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-30 19:41 [PATCH 0/7] uprobes: register/unregister bugfixes Oleg Nesterov
2012-09-30 19:41 ` [PATCH 1/7] uprobes/x86: Only rep+nop can be emulated correctly Oleg Nesterov
2012-10-06 7:20 ` Srikar Dronamraju
2012-09-30 19:42 ` [PATCH 2/7] uprobes: Don't return success if alloc_uprobe() fails Oleg Nesterov
2012-10-06 7:25 ` Srikar Dronamraju
2012-09-30 19:42 ` [PATCH 3/7] uprobes: Do not delete uprobe if uprobe_unregister() fails Oleg Nesterov
2012-10-06 8:48 ` Srikar Dronamraju
2012-09-30 19:42 ` [PATCH 4/7] uprobes: Fix handle_swbp() vs unregister() + register() race Oleg Nesterov
2012-10-02 18:42 ` Oleg Nesterov
2012-10-06 9:33 ` Srikar Dronamraju
2012-10-06 17:25 ` Oleg Nesterov
2012-10-06 17:37 ` Srikar Dronamraju
2012-10-06 18:53 ` Oleg Nesterov
2012-10-07 7:12 ` Srikar Dronamraju
2012-09-30 19:42 ` [PATCH 5/7] uprobes: Introduce uprobe_copy_insn() Oleg Nesterov
2012-10-06 9:45 ` Srikar Dronamraju
2012-10-06 17:10 ` Oleg Nesterov
2012-10-06 17:38 ` Srikar Dronamraju
2012-10-06 18:59 ` Oleg Nesterov
2012-10-07 7:14 ` Srikar Dronamraju
2012-09-30 19:42 ` [PATCH 6/7] uprobes: Fix uprobe_copy_insn() race with itself Oleg Nesterov
2012-10-06 9:52 ` Srikar Dronamraju [this message]
2012-09-30 19:42 ` [PATCH 7/7] uprobes: Fix the racy uprobe->flags manipulation Oleg Nesterov
2012-10-04 8:57 ` Anton Arapov
2012-10-06 9:54 ` Srikar Dronamraju
2012-09-30 19:44 ` [PATCH 0/7] uprobes: register/unregister bugfixes Oleg Nesterov
2012-10-01 12:55 ` Srikar Dronamraju
2012-10-01 14:03 ` Oleg Nesterov
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