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Date: Fri, 28 Feb 2003 13:23:22 -0800
From: Andrew Morton <akpm@digeo.com>
To: Petr Vandrovec <vandrove@vc.cvut.cz>
Cc: linux-kernel@vger.kernel.org, Hugh Dickins <hugh@veritas.com>
Subject: Re: Memory modified after freeing in 2.5.63?
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Petr Vandrovec <vandrove@vc.cvut.cz> wrote:
>
> Hi,
>   for some time I'm using patch attached at the end of this email, 
> which modifies check_poison function to not only verify that
> last byte is POISON_END, but also that all preceeding bytes are
> either POISON_BEFORE or POISON_AFTER bytes. 

Nice patch.

>   And now when I returned from my month vacation and upgraded 
> from 2.5.52 to 2.5.63, when dselect/apt updates dozens of packages, 
> I'm getting memory corruption reports as shown below - 22nd byte 
> in vm_area_struct - which looks like that VM_ACCOUNT in vm_flags 
> is set after vma is freeed...  Any clue? Setting VM_ACCOUNT
> in mremap.c:move_vma after calling do_unmap() looks suspicious
> to me, but as I know almost nothing about MM...

Ha!  I've been harrassing Hugh over this ;)

Thanks.


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