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From: Nick Piggin <nickpiggin@yahoo.com.au>
To: "Robert Bragg" <robert@sixbynine.org>
Subject: Re: [PATCH] mm: Don't allow ioremapping of ranges larger than vmalloc space
Date: Wed, 14 Nov 2007 20:16:14 +1100
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Cc: "Andrew Morton" <akpm@linux-foundation.org>, linux-mm@kvack.org,
       linux-kernel@vger.kernel.org
References: <e04d66f60711141031waeb9f1bu34a8fa4cadd5d6c3@mail.gmail.com>
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On Thursday 15 November 2007 05:31, Robert Bragg wrote:
> When running with a 16M IOREMAP_MAX_ORDER (on armv7) we found that the
> vmlist search routine in __get_vm_area_node can mistakenly allow a driver
> to ioremap a range larger than vmalloc space.
>
> If at the time of the ioremap all existing vmlist areas sit below the
> determined alignment then the search routine continues past all entries and
> exits the for loop - straight into the found: label - without ever testing
> for integer wrapping or that the requested size fits.
>
> We were seeing a driver successfully ioremap 128M of flash even though
> there was only 120M of vmalloc space. From that point the system was left
> with the remainder
> of the first 16M of space to vmalloc/ioremap within.
>
> Signed-off-by: Robert Bragg <robert@sixbynine.org>
>
> ---
>
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index af77e17..06a7f3a 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -216,6 +216,10 @@ static struct vm_struct *__get_vm_area_node
>  		if (addr > end - size)
>  			goto out;
>  	}
> +	if ((size + addr) < addr)
> +		goto out;
> +	if (addr > end - size)
> +		goto out;
>
>  found:
>  	area->next = *p;

Yeah I noticed these missing checks when recently working in
this area as well. Weren't sure if I was missing something or
not.

Acked-by: Nick Piggin <npiggin@suse.de>
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