linux-kernel - Re: [PATCH] arm64: mm: Ensure tail of unaligned initrd is reserved

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Date:   Tue, 23 Apr 2019 10:56:05 +0100
From:   Will Deacon <will.deacon@....com>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Florian Fainelli <f.fainelli@...il.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org
Subject: Re: [PATCH] arm64: mm: Ensure tail of unaligned initrd is reserved

On Wed, Apr 17, 2019 at 09:29:29PM -0700, Bjorn Andersson wrote:
> In the event that the start address of the initrd is not aligned, but
> has an aligned size, the base + size will not cover the entire initrd
> image and there is a chance that the kernel will corrupt the tail of the
> image.
> 
> By aligning the end of the initrd to a page boundary and then
> subtracting the adjusted start address the memblock reservation will
> cover all pages that contains the initrd.
> 
> Fixes: c756c592e442 ("arm64: Utilize phys_initrd_start/phys_initrd_size")
> Cc: stable@...r.kernel.org
> Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>
> ---
>  arch/arm64/mm/init.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index 6bc135042f5e..7cae155e81a5 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -363,7 +363,7 @@ void __init arm64_memblock_init(void)
>  		 * Otherwise, this is a no-op
>  		 */
>  		u64 base = phys_initrd_start & PAGE_MASK;
> -		u64 size = PAGE_ALIGN(phys_initrd_size);
> +		u64 size = PAGE_ALIGN(phys_initrd_start + phys_initrd_size) - base;

Acked-by: Will Deacon <will.deacon@....com>

Catalin can pick this up as a fix for 5.1.

Will