linux-kernel - Re: [PATCH 3/5] uprobes: fix overflow in vma_address/find_active

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Message-ID: <1341782304.13174.21.camel@joe2Laptop>
Date:	Sun, 08 Jul 2012 14:18:24 -0700
From:	Joe Perches <joe@...ches.com>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Ingo Molnar <mingo@...e.hu>,
	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Anton Arapov <anton@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/5] uprobes: fix overflow in
 vma_address/find_active_uprobe

On Sun, 2012-07-08 at 22:30 +0200, Oleg Nesterov wrote:
> vma->vm_pgoff is "unsigned long", it should be promoted to loff_t
> before the multiplication to avoid the overflow.
[]
> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
[]
> @@ -117,7 +117,7 @@ static loff_t vma_address(struct vm_area_struct *vma, loff_t offset)
>  	loff_t vaddr;
>  
>  	vaddr = vma->vm_start + offset;
> -	vaddr -= vma->vm_pgoff << PAGE_SHIFT;
> +	vaddr -= (loff_t)vma->vm_pgoff << PAGE_SHIFT;
>  
>  	return vaddr;
>  }
> @@ -1450,7 +1450,7 @@ static struct uprobe *find_active_uprobe(unsigned long bp_vaddr, int *is_swbp)
>  
>  			inode = vma->vm_file->f_mapping->host;
>  			offset = bp_vaddr - vma->vm_start;
> -			offset += (vma->vm_pgoff << PAGE_SHIFT);
> +			offset += ((loff_t)vma->vm_pgoff << PAGE_SHIFT);

It's be nice to take remove the unnecessary parenthesis
and make it consistent with the vaddr use above it too.


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