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

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Message-ID: <20120709105445.GA32699@redhat.com>
Date:	Mon, 9 Jul 2012 12:54:45 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Joe Perches <joe@...ches.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 07/08, Joe Perches wrote:
>
> On Sun, 2012-07-08 at 22:30 +0200, Oleg Nesterov wrote:
> > @@ -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.

OK, please find v2 below.

------------------------------------------------------------------------------
Subject: [PATCH] uprobes: fix overflow in vma_address/find_active_uprobe

vma->vm_pgoff is "unsigned long", it should be promoted to loff_t
before the multiplication to avoid the overflow.

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 kernel/events/uprobes.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 47c4e24..6194edb 100644
--- 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;
 			uprobe = find_uprobe(inode, offset);
 		}
 
-- 
1.5.5.1


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