Re: [PATCH] efi/libstub/x86: Free EFI map buffer in allocate_e820()

[Lenny Szubowicz]

On 5/6/20 3:23 AM, Ard Biesheuvel wrote:
> On Tue, 5 May 2020 at 21:00, Lenny Szubowicz <lszubowi@xxxxxxxxxx> wrote:
> > In allocate_e820(), free the EFI map buffer that has been returned
> > by efi_get_memory_map(). The returned size of the EFI map buffer
> > is used to allocate an adequately sized e820ext buffer, if it's
> > needed. But the contents of that EFI map buffer is not used at all
> > and the local pointer to it is gone on return from allocate_e820().
> >
> > Signed-off-by: Lenny Szubowicz <lszubowi@xxxxxxxxxx>
> > ---
> >   drivers/firmware/efi/libstub/x86-stub.c | 3 +++
> >   1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/firmware/efi/libstub/x86-stub.c b/drivers/firmware/efi/libstub/x86-stub.c
> > index 05ccb229fb45..4efe3e7a218d 100644
> > --- a/drivers/firmware/efi/libstub/x86-stub.c
> > +++ b/drivers/firmware/efi/libstub/x86-stub.c
> > @@ -623,6 +623,9 @@ static efi_status_t allocate_e820(struct boot_params *params,
> >          if (status != EFI_SUCCESS)
> >                  return status;
> >
> > +       /* Allocated EFI map buf is not used here. Just need its size. */
> > +       efi_bs_call(free_pool, map);
> > +
>
> Wouldn't it be better to call BS->GetMemoryMap() directly here, with a
> zero size for the input buffer?

I agree, that's a good suggestion. V2 coming shortly after testing.

> >          nr_desc = buff_size / desc_size;
> >
> >          if (nr_desc > ARRAY_SIZE(params->e820_table)) {
> > --
> > 2.18.4