On Wed, 29 Oct 2014 17:09:32 +0100
, Ard Biesheuvel <[email protected]>
wrote:
> Memory regions passed to early_init_dt_add_memory_arch() are rounded to
> PAGE_SIZE by subtracting the size of the leading fractional page from
> the 'size' argument. However, size being a u64 type, if its value is
> sufficiently small, the subtraction wraps around and produces a bogus
> value, potentially leading to crashes.
>
> Fix this by ignoring the memory range in such cases.
>
> Signed-off-by: Ard Biesheuvel <[email protected]>
Applied, thanks.
g.
> ---
> drivers/of/fdt.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index d1ffca8b34ea..3b423f5b99c6 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -930,6 +930,11 @@ void __init __weak early_init_dt_add_memory_arch(u64
> base, u64 size)
> const u64 phys_offset = __pa(PAGE_OFFSET);
>
> if (!PAGE_ALIGNED(base)) {
> + if (size < PAGE_SIZE - (base & ~PAGE_MASK)) {
> + pr_warn("Ignoring memory block 0x%llx - 0x%llx\n",
> + base, base + size);
> + return;
> + }
> size -= PAGE_SIZE - (base & ~PAGE_MASK);
> base = PAGE_ALIGN(base);
> }
> --
> 1.8.3.2
>
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