[PATCH] arm64: mm: Ensure tail of unaligned initrd is reserved

[PATCH] arm64: mm: Ensure tail of unaligned initrd is reserved

[Bjorn Andersson]

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@vger.kernel.org
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.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;
 
 		/*
 		 * We can only add back the initrd memory if we don't end up
-- 
2.18.0

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

[Will Deacon]

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@vger.kernel.org
> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.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@arm.com>

Catalin can pick this up as a fix for 5.1.

Will