[PATCH] arm64: setup: Check for overlapping dtb and Image load addresses

[Julien Thierry]

Hi Lingutla,

On 19/01/18 06:56, Lingutla Chandrasekhar wrote:
> Sometime kernel image and dtb load offsets can overlap due to
> dynamically increased Image or dtb size if both load addresses
> are near to each other, which leads to bootup failures.
> 
> So validate dtb load address and kernel image, if they overlap
> do not proceed to boot.
> 
> Signed-off-by: Lingutla Chandrasekhar <clingutla at codeaurora.org>
> 
> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
> index 30ad2f085d1f..c9dd699f09ab 100644
> --- a/arch/arm64/kernel/setup.c
> +++ b/arch/arm64/kernel/setup.c
> @@ -181,11 +181,17 @@ static void __init smp_build_mpidr_hash(void)
>   static void __init setup_machine_fdt(phys_addr_t dt_phys)
>   {
>   	void *dt_virt = fixmap_remap_fdt(dt_phys);
> +	u64 end_phys = __pa_symbol(_end);
> +	u64 start_phys = __pa_symbol(_text);
>   	const char *name;
>   
> -	if (!dt_virt || !early_init_dt_scan(dt_virt)) {
> +	if (!dt_virt || ((dt_phys < start_phys) &&
> +		((dt_phys + fdt_totalsize(dt_virt)) > start_phys)) ||
> +		((dt_phys > start_phys) && (dt_phys < end_phys)) ||
> +		!early_init_dt_scan(dt_virt)) {
>   		pr_crit("\n"
>   			"Error: invalid device tree blob at physical address %pa (virtual address 0x%p)\n"
> +			"The dtb load address should not overlap with kernel image\n"
>   			"The dtb must be 8-byte aligned and must not exceed 2 MB in size\n"
>   			"\nPlease check your bootloader.",
>   			&dt_phys, dt_virt);
> 

Could this be checked separately?

When you get that error message you don't know whether the issue is an 
ill formed dtb or overlapping with the kernel.

So it'd be nice to have a separate message (and maybe add info of how 
many bytes are overlapping?).

Cheers,

-- 
Julien Thierry