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

Mike Rapoport
2026-03-20T14:08:47Z

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.

@Ard, can you please pick the fix:

From 8fc5c5e828e7d127e6210bc9952451300591cdce Mon Sep 17 00:00:00 2001
From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>
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@roeck-us.net>
Fixes: a4b0bf6a40f3 ("x86/efi: defer freeing of boot services memory")
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
---
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");
--
2.53.0