Re: [PATCH RESEND] x86/boot: Fix off-by-one error in sme_clear_pgd()

[Tom Lendacky]

On 9/18/26 09:27, Thorsten Blum wrote:
> The mapping helpers __sme_map_range_pmd() and __sme_map_range_pte(), and
> therefore sme_encrypt_kernel(), use exclusive end addresses and stop
> before vaddr reaches vaddr_end.
> 
> However, sme_clear_pgd() treats vaddr_end as inclusive when calculating
> the last PGD entry to clear. If vaddr_end is PGD-aligned, the first PGD
> entry outside the range is cleared too.
> 
> Use vaddr_end - 1 to calculate the last PGD entry within the range.
> 
> Fixes: 6ebcb060713f ("x86/mm: Add support to encrypt the kernel in-place")
> Signed-off-by: Thorsten Blum <blum@xxxxxxxxxx>

Reviewed-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
> ---
>  arch/x86/boot/startup/sme.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/boot/startup/sme.c b/arch/x86/boot/startup/sme.c
> index c07a2c381ed1..2d5cb3f7eee6 100644
> --- a/arch/x86/boot/startup/sme.c
> +++ b/arch/x86/boot/startup/sme.c
> @@ -99,7 +99,7 @@ static void __init sme_clear_pgd(struct sme_populate_pgd_data *ppd)
>  	pgd_t *pgd_p;
>  
>  	pgd_start = ppd->vaddr & PGDIR_MASK;
> -	pgd_end = ppd->vaddr_end & PGDIR_MASK;
> +	pgd_end = (ppd->vaddr_end - 1) & PGDIR_MASK;
>  
>  	pgd_size = (((pgd_end - pgd_start) / PGDIR_SIZE) + 1) * sizeof(pgd_t);
>