linux-kernel - Re: [PATCH 1/5] uprobes: Do not leak UTASK_BP_HIT if find_active

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Date:	Thu, 20 Sep 2012 19:23:51 +0530
From:	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Ingo Molnar <mingo@...e.hu>, Peter Zijlstra <peterz@...radead.org>,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Anton Arapov <anton@...hat.com>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/5] uprobes: Do not leak UTASK_BP_HIT if
 find_active_uprobe() fails

> If handle_swbp()->find_active_uprobe() fails we return with
> utask->state = UTASK_BP_HIT.
> 
> Change handle_swbp() to reset utask->state at the start. Note
> that we do this unconditionally, see the next patch(es).
> 
> Signed-off-by: Oleg Nesterov <oleg@...hat.com>
> ---
>  kernel/events/uprobes.c |    5 ++++-
>  1 files changed, 4 insertions(+), 1 deletions(-)
> 
> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
> index 26f06a6..760acc1 100644
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -1468,6 +1468,10 @@ static void handle_swbp(struct pt_regs *regs)
>  	bp_vaddr = uprobe_get_swbp_addr(regs);
>  	uprobe = find_active_uprobe(bp_vaddr, &is_swbp);
> 
> +	utask = current->utask;
> +	if (utask)
> +		utask->state = UTASK_RUNNING;
> +
>  	if (!uprobe) {
>  		if (is_swbp > 0) {
>  			/* No matching uprobe; signal SIGTRAP. */
> @@ -1486,7 +1490,6 @@ static void handle_swbp(struct pt_regs *regs)
>  		return;
>  	}
> 
> -	utask = current->utask;
>  	if (!utask) {
>  		utask = add_utask();
>  		/* Cannot allocate; re-execute the instruction. */


Acked-by: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>

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