linux-kernel - Re: [PATCH] mm: Don't allow ioremapping of ranges larger than vmalloc space

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Message-Id: <200711142016.14931.nickpiggin@yahoo.com.au>
Date:	Wed, 14 Nov 2007 20:16:14 +1100
From:	Nick Piggin <nickpiggin@...oo.com.au>
To:	"Robert Bragg" <robert@...bynine.org>
Cc:	"Andrew Morton" <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: Don't allow ioremapping of ranges larger than vmalloc space

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@...bynine.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@...e.de>
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