Re: [PATCH] x86/acpi: fix potential NULL deref in acpi_wakeup_cpu()

[Sathyanarayanan Kuppuswamy]

On 4/11/25 12:48 PM, Chenyuan Yang wrote:
> The result of memremap() may be NULL on failure, leading to a NULL
> dereference. Add explicit checks after memremap() call: if the
> MADT mailbox fails to map, return immediately.
>
> This is similar to the commit 966d47e1f27c
> ("efi: fix potential NULL deref in efi_mem_reserve_persistent").
>
> This is found by our static analysis tool KNighter.
>
> Signed-off-by: Chenyuan Yang <chenyuan0y@xxxxxxxxx>
> Fixes: 2b5e22afae07 ("x86/acpi: Extract ACPI MADT wakeup code into a separate file")
> ---

Looks fine to me

Reviewed-by: Kuppuswamy Sathyanarayanan 
<sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>

>   arch/x86/kernel/acpi/madt_wakeup.c | 4 ++++
>   1 file changed, 4 insertions(+)
>
> diff --git a/arch/x86/kernel/acpi/madt_wakeup.c b/arch/x86/kernel/acpi/madt_wakeup.c
> index f36f28405dcc..b386ec4b87c2 100644
> --- a/arch/x86/kernel/acpi/madt_wakeup.c
> +++ b/arch/x86/kernel/acpi/madt_wakeup.c
> @@ -143,6 +143,10 @@ static int acpi_wakeup_cpu(u32 apicid, unsigned long start_ip)
>   		acpi_mp_wake_mailbox = memremap(acpi_mp_wake_mailbox_paddr,
>   						sizeof(*acpi_mp_wake_mailbox),
>   						MEMREMAP_WB);
> +		if (!acpi_mp_wake_mailbox) {
> +			pr_err("Failed to remap MADT mailbox\n");
> +			return -ENOMEM;
> +		}
>   	}
>   
>   	/*

--
Sathyanarayanan Kuppuswamy
Linux Kernel Developer