linux-kernel - Re: [PATCH 5/7] uprobes: Fix utask->xol_vaddr leak in pre

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Message-ID: <20130108121328.GH1325@linux.vnet.ibm.com>
Date:	Tue, 8 Jan 2013 17:43:28 +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>,
	Frank Eigler <fche@...hat.com>,
	Josh Stone <jistone@...hat.com>,
	"Suzuki K. Poulose" <suzuki@...ibm.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/7] uprobes: Fix utask->xol_vaddr leak in pre_ssout()

* Oleg Nesterov <oleg@...hat.com> [2012-12-31 18:52:26]:

> pre_ssout() should do xol_free_insn_slot() if arch_uprobe_pre_xol()
> fails, otherwise nobody will free the allocated slot.
> 
> Signed-off-by: Oleg Nesterov <oleg@...hat.com>

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

(one nit below)
> ---
>  kernel/events/uprobes.c |    9 ++++++++-
>  1 files changed, 8 insertions(+), 1 deletions(-)
> 
> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
> index 2ed6239..bd94d2c 100644
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -1306,6 +1306,7 @@ pre_ssout(struct uprobe *uprobe, struct pt_regs *regs, unsigned long bp_vaddr)
>  {
>  	struct uprobe_task *utask;
>  	unsigned long xol_vaddr;
> +	int err;
> 
>  	utask = current->utask;
> 
> @@ -1316,7 +1317,13 @@ pre_ssout(struct uprobe *uprobe, struct pt_regs *regs, unsigned long bp_vaddr)
>  	utask->xol_vaddr = xol_vaddr;
>  	utask->vaddr = bp_vaddr;
> 
> -	return arch_uprobe_pre_xol(&uprobe->arch, regs);
> +	err = arch_uprobe_pre_xol(&uprobe->arch, regs);
> +	if (unlikely(err)) {
> +		xol_free_insn_slot(current);
> +		return err;
> +	}
> +
> +	return 0;
>  }

Nit: we could reduce a line or two with

	err = arch_uprobe_pre_xol(&uprobe->arch, regs);
	if (unlikely(err))
		xol_free_insn_slot(current);

	return err;
> 
>  /*
> -- 
> 1.5.5.1
> 

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