Re: [PATCH v7 1/3] efi/x86: Fix EFI memory map corruption with kexec
From: Dave Young
Date: Tue Jun 04 2024 - 21:58:54 EST
On Wed, 5 Jun 2024 at 09:52, Dave Young <dyoung@xxxxxxxxxx> wrote:
>
> > > ...
> > > if (efi.memmap.flags & (EFI_MEMMAP_MEMBLOCK | EFI_MEMMAP_SLAB)) {
> > > __efi_memmap_free(efi.memmap.phys_map,
> > > efi.memmap.desc_size * efi.memmap.nr_map, efi.memmap.flags);
> > > }
> >
> > From your debugging the memmap should not be freed. This piece of
> > code was added in below commit, added Dan Williams in cc list:
> > commit f0ef6523475f18ccd213e22ee593dfd131a2c5ea
> > Author: Dan Williams <dan.j.williams@xxxxxxxxx>
> > Date: Mon Jan 13 18:22:44 2020 +0100
> >
> > efi: Fix efi_memmap_alloc() leaks
> >
> > With efi_fake_memmap() and efi_arch_mem_reserve() the efi table may be
> > updated and replaced multiple times. When that happens a previous
> > dynamically allocated efi memory map can be garbage collected. Use the
> > new EFI_MEMMAP_{SLAB,MEMBLOCK} flags to detect when a dynamically
> > allocated memory map is being replaced.
> >
>
> Dan, probably those regions should be freed only for "fake" memmap?
Ashish, can you comment out the __efi_memmap_free see if it works for
you just confirm about the behavior.