linux-kernel - Re: [PATCH v2 1/4] highmem: Enhance is_kmap_addr() to check kmap_local

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Date:   Mon, 13 Feb 2023 16:53:28 +0100
From:   Jens Wiklander <jens.wiklander@...aro.org>
To:     Ira Weiny <ira.weiny@...el.com>
Cc:     Sumit Garg <sumit.garg@...aro.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Al Viro <viro@...iv.linux.org.uk>,
        Christoph Hellwig <hch@....de>, linux-kernel@...r.kernel.org,
        op-tee@...ts.trustedfirmware.org, linux-mm@...ck.org,
        "Fabio M. De Francesco" <fmdefrancesco@...il.com>,
        John Hubbard <jhubbard@...dia.com>,
        Matthew Wilcox <willy@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v2 1/4] highmem: Enhance is_kmap_addr() to check
 kmap_local_page() mappings

On Fri, Feb 03, 2023 at 08:06:32PM -0800, Ira Weiny wrote:
> is_kmap_addr() is only looking at the kmap() address range which may
> cause check_heap_object() to miss checking an overflow on a
> kmap_local_page() page.
> 
> Add a check for the kmap_local_page() address range to is_kmap_addr().
> 
> Cc: Matthew Wilcox <willy@...radead.org>
> Cc: Al Viro <viro@...iv.linux.org.uk>
> Cc: "Fabio M. De Francesco" <fmdefrancesco@...il.com>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Christoph Hellwig <hch@....de>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Signed-off-by: Ira Weiny <ira.weiny@...el.com>
> ---
>  include/linux/highmem-internal.h | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 

Added to https://git.linaro.org/people/jens.wiklander/linux-tee.git/log/?h=get_kernel_pages-for-v6.4

Thanks,
Jens

> diff --git a/include/linux/highmem-internal.h b/include/linux/highmem-internal.h
> index e098f38422af..a3028e400a9c 100644
> --- a/include/linux/highmem-internal.h
> +++ b/include/linux/highmem-internal.h
> @@ -152,7 +152,10 @@ static inline void totalhigh_pages_add(long count)
>  static inline bool is_kmap_addr(const void *x)
>  {
>  	unsigned long addr = (unsigned long)x;
> -	return addr >= PKMAP_ADDR(0) && addr < PKMAP_ADDR(LAST_PKMAP);
> +
> +	return (addr >= PKMAP_ADDR(0) && addr < PKMAP_ADDR(LAST_PKMAP)) ||
> +		(addr >= __fix_to_virt(FIX_KMAP_END) &&
> +		 addr < __fix_to_virt(FIX_KMAP_BEGIN));
>  }
>  #else /* CONFIG_HIGHMEM */
>  
> 
> -- 
> 2.39.1