linux-kernel - Re: [Patch v3 01/14] x86/ioremap: Fix page aligned size calculation in __ioremap

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Date:   Mon, 21 Nov 2022 14:32:54 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Michael Kelley <mikelley@...rosoft.com>
Cc:     hpa@...or.com, kys@...rosoft.com, haiyangz@...rosoft.com,
        wei.liu@...nel.org, decui@...rosoft.com, luto@...nel.org,
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        iommu@...ts.linux.dev
Subject: Re: [Patch v3 01/14] x86/ioremap: Fix page aligned size calculation
 in __ioremap_caller()

On Wed, Nov 16, 2022 at 10:41:24AM -0800, Michael Kelley wrote:
> Current code re-calculates the size after aligning the starting and
> ending physical addresses on a page boundary. But the re-calculation
> also embeds the masking of high order bits that exceed the size of
> the physical address space (via PHYSICAL_PAGE_MASK). If the masking
> removes any high order bits, the size calculation results in a huge
> value that is likely to immediately fail.
> 
> Fix this by re-calculating the page-aligned size first. Then mask any
> high order bits using PHYSICAL_PAGE_MASK.
> 
> Signed-off-by: Michael Kelley <mikelley@...rosoft.com>
> ---
>  arch/x86/mm/ioremap.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
> index 78c5bc6..6453fba 100644
> --- a/arch/x86/mm/ioremap.c
> +++ b/arch/x86/mm/ioremap.c
> @@ -217,9 +217,15 @@ static void __ioremap_check_mem(resource_size_t addr, unsigned long size,
>  	 * Mappings have to be page-aligned
>  	 */
>  	offset = phys_addr & ~PAGE_MASK;
> -	phys_addr &= PHYSICAL_PAGE_MASK;
> +	phys_addr &= PAGE_MASK;
>  	size = PAGE_ALIGN(last_addr+1) - phys_addr;
>  
> +	/*
> +	 * Mask out any bits not part of the actual physical
> +	 * address, like memory encryption bits.
> +	 */
> +	phys_addr &= PHYSICAL_PAGE_MASK;
> +
>  	retval = memtype_reserve(phys_addr, (u64)phys_addr + size,
>  						pcm, &new_pcm);
>  	if (retval) {
> -- 

This looks like a fix to me that needs to go to independently to stable.
And it would need a Fixes tag.

/me does some git archeology...

I guess this one:

ffa71f33a820 ("x86, ioremap: Fix incorrect physical address handling in PAE mode")

should be old enough so that it goes to all relevant stable kernels...

Hmm?

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette