Re: [PATCH v2] x86/efi: defer freeing of boot services memory

[Guenter Roeck]

On 3/20/26 07:08, Mike Rapoport wrote:
> On Thu, Mar 19, 2026 at 09:06:52PM -0700, Guenter Roeck wrote:
> > Hi,
> >
> > > +void __init efi_unmap_boot_services(void)
> > >   {
> > >   	struct efi_memory_map_data data = { 0 };
> > >   	efi_memory_desc_t *md;
> > >   	int num_entries = 0;
> > > +	int idx = 0;
> > > +	size_t sz;
> > >   	void *new, *new_md;
> > >   
> > >   	/* Keep all regions for /sys/kernel/debug/efi */
> > >   	if (efi_enabled(EFI_DBG))
> > >   		return;
> > >   
> > > +	sz = sizeof(*ranges_to_free) * efi.memmap.nr_map + 1;
> >
> > Was this possibly supposed to be
> > 	sz = sizeof(*ranges_to_free) * (efi.memmap.nr_map + 1);
> > 				       ^		     ^
> > ?
>
> Yes, thanks for catching this.
>   

Thanks for confirming.

Just for the record, it wasn't really me, it was an instance of Sashiko
running on the LTS backport of the patch.

Guenter

> @Ard, can you please pick the fix:
>
>  From 8fc5c5e828e7d127e6210bc9952451300591cdce Mon Sep 17 00:00:00 2001
> From: "Mike Rapoport (Microsoft)" <rppt@xxxxxxxxxx>
> Date: Fri, 20 Mar 2026 15:59:48 +0200
> Subject: [PATCH] x86/efi: efi_unmap_boot_services: fix calculation of
>   ranges_to_free size
>
> ranges_to_free array should have enough room to store the entire EFI
> memmap plus an extra element for NULL entry.
> The calculation of this array size wrongly adds 1 to the overall size
> instead of adding 1 to the number of elements.
>
> Add parentheses to properly size the array.
>
> Reported-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> Fixes: a4b0bf6a40f3 ("x86/efi: defer freeing of boot services memory")
> Signed-off-by: Mike Rapoport (Microsoft) <rppt@xxxxxxxxxx>
> ---
>   arch/x86/platform/efi/quirks.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c
> index 35caa5746115..79f0818131e8 100644
> --- a/arch/x86/platform/efi/quirks.c
> +++ b/arch/x86/platform/efi/quirks.c
> @@ -424,7 +424,7 @@ void __init efi_unmap_boot_services(void)
>   	if (efi_enabled(EFI_DBG))
>   		return;
>   
> -	sz = sizeof(*ranges_to_free) * efi.memmap.nr_map + 1;
> +	sz = sizeof(*ranges_to_free) * (efi.memmap.nr_map + 1);
>   	ranges_to_free = kzalloc(sz, GFP_KERNEL);
>   	if (!ranges_to_free) {
>   		pr_err("Failed to allocate storage for freeable EFI regions\n");