Re: [PATCH v3 2/4] efi: Add tracking for dynamically allocated memmaps

[Dan Williams]

On Thu, Jan 2, 2020 at 1:02 AM Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> wrote:
>
> Hi Dan,
>
> Thanks for taking the time to really fix this properly.
>
> Comments/questions below.
>
> On Thu, 2 Jan 2020 at 05:29, Dan Williams <dan.j.williams@xxxxxxxxx> wrote:
> >
> > In preparation for fixing efi_memmap_alloc() leaks, add support for
> > recording whether the memmap was dynamically allocated from slab,
> > memblock, or is the original physical memmap provided by the platform.
> >
> > Cc: Taku Izumi <izumi.taku@xxxxxxxxxxxxxx>
> > Cc: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
> > Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
> > ---
> >  arch/x86/platform/efi/efi.c     |    2 +-
> >  arch/x86/platform/efi/quirks.c  |   11 ++++++-----
> >  drivers/firmware/efi/fake_mem.c |    5 +++--
> >  drivers/firmware/efi/memmap.c   |   16 ++++++++++------
> >  include/linux/efi.h             |    8 ++++++--
> >  5 files changed, 26 insertions(+), 16 deletions(-)
> >
> > diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
> > index 38d44f36d5ed..7086afbb84fd 100644
> > --- a/arch/x86/platform/efi/efi.c
> > +++ b/arch/x86/platform/efi/efi.c
> > @@ -333,7 +333,7 @@ static void __init efi_clean_memmap(void)
> >                 u64 size = efi.memmap.nr_map - n_removal;
> >
> >                 pr_warn("Removing %d invalid memory map entries.\n", n_removal);
> > -               efi_memmap_install(efi.memmap.phys_map, size);
> > +               efi_memmap_install(efi.memmap.phys_map, size, 0);
> >         }
> >  }
> >
> > diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c
> > index f8f0220b6a66..4a71c790f9c3 100644
> > --- a/arch/x86/platform/efi/quirks.c
> > +++ b/arch/x86/platform/efi/quirks.c
> > @@ -244,6 +244,7 @@ EXPORT_SYMBOL_GPL(efi_query_variable_store);
> >  void __init efi_arch_mem_reserve(phys_addr_t addr, u64 size)
> >  {
> >         phys_addr_t new_phys, new_size;
> > +       unsigned long flags = 0;
> >         struct efi_mem_range mr;
> >         efi_memory_desc_t md;
> >         int num_entries;
> > @@ -272,8 +273,7 @@ void __init efi_arch_mem_reserve(phys_addr_t addr, u64 size)
> >         num_entries += efi.memmap.nr_map;
> >
> >         new_size = efi.memmap.desc_size * num_entries;
> > -
> > -       new_phys = efi_memmap_alloc(num_entries);
> > +       new_phys = efi_memmap_alloc(num_entries, &flags);
> >         if (!new_phys) {
> >                 pr_err("Could not allocate boot services memmap\n");
> >                 return;
> > @@ -288,7 +288,7 @@ void __init efi_arch_mem_reserve(phys_addr_t addr, u64 size)
> >         efi_memmap_insert(&efi.memmap, new, &mr);
> >         early_memunmap(new, new_size);
> >
> > -       efi_memmap_install(new_phys, num_entries);
> > +       efi_memmap_install(new_phys, num_entries, flags);
> >         e820__range_update(addr, size, E820_TYPE_RAM, E820_TYPE_RESERVED);
> >         e820__update_table(e820_table);
> >  }
> > @@ -408,6 +408,7 @@ static void __init efi_unmap_pages(efi_memory_desc_t *md)
> >  void __init efi_free_boot_services(void)
> >  {
> >         phys_addr_t new_phys, new_size;
> > +       unsigned long flags = 0;
> >         efi_memory_desc_t *md;
> >         int num_entries = 0;
> >         void *new, *new_md;
> > @@ -463,7 +464,7 @@ void __init efi_free_boot_services(void)
> >                 return;
> >
> >         new_size = efi.memmap.desc_size * num_entries;
> > -       new_phys = efi_memmap_alloc(num_entries);
> > +       new_phys = efi_memmap_alloc(num_entries, &flags);
> >         if (!new_phys) {
> >                 pr_err("Failed to allocate new EFI memmap\n");
> >                 return;
> > @@ -493,7 +494,7 @@ void __init efi_free_boot_services(void)
> >
> >         memunmap(new);
> >
> > -       if (efi_memmap_install(new_phys, num_entries)) {
> > +       if (efi_memmap_install(new_phys, num_entries, flags)) {
> >                 pr_err("Could not install new EFI memmap\n");
> >                 return;
> >         }
> > diff --git a/drivers/firmware/efi/fake_mem.c b/drivers/firmware/efi/fake_mem.c
> > index bb9fc70d0cfa..7e53e5520548 100644
> > --- a/drivers/firmware/efi/fake_mem.c
> > +++ b/drivers/firmware/efi/fake_mem.c
> > @@ -39,6 +39,7 @@ void __init efi_fake_memmap(void)
> >         int new_nr_map = efi.memmap.nr_map;
> >         efi_memory_desc_t *md;
> >         phys_addr_t new_memmap_phy;
> > +       unsigned long flags = 0;
> >         void *new_memmap;
> >         int i;
> >
> > @@ -55,7 +56,7 @@ void __init efi_fake_memmap(void)
> >         }
> >
> >         /* allocate memory for new EFI memmap */
> > -       new_memmap_phy = efi_memmap_alloc(new_nr_map);
> > +       new_memmap_phy = efi_memmap_alloc(new_nr_map, &flags);
> >         if (!new_memmap_phy)
> >                 return;
> >
> > @@ -73,7 +74,7 @@ void __init efi_fake_memmap(void)
> >         /* swap into new EFI memmap */
> >         early_memunmap(new_memmap, efi.memmap.desc_size * new_nr_map);
> >
> > -       efi_memmap_install(new_memmap_phy, new_nr_map);
> > +       efi_memmap_install(new_memmap_phy, new_nr_map, flags);
> >
>
> So it is the caller's responsibility to record the flags returned by
> efi_memmap_alloc() and pass them into efi_memmap_install(), right?
> Given that we are now passing three pieces of info that need to be in
> sync between the two, could we use a dedicated data structure instead,
> a reference to which is taken by both?

Sounds good, looks like I can mostly reuse 'struct
efi_memory_map_data' for this purpose.

>
>
> >         /* print new EFI memmap */
> >         efi_print_memmap();
> > diff --git a/drivers/firmware/efi/memmap.c b/drivers/firmware/efi/memmap.c
> > index 813674ef9000..2b81ee6858a9 100644
> > --- a/drivers/firmware/efi/memmap.c
> > +++ b/drivers/firmware/efi/memmap.c
> > @@ -32,6 +32,7 @@ static phys_addr_t __init __efi_memmap_alloc_late(unsigned long size)
> >  /**
> >   * efi_memmap_alloc - Allocate memory for the EFI memory map
> >   * @num_entries: Number of entries in the allocated map.
> > + * @flags: Late map, memblock alloc, slab alloc flags
> >   *
> >   * Depending on whether mm_init() has already been invoked or not,
> >   * either memblock or "normal" page allocation is used.
> > @@ -39,20 +40,23 @@ static phys_addr_t __init __efi_memmap_alloc_late(unsigned long size)
> >   * Returns the physical address of the allocated memory map on
> >   * success, zero on failure.
> >   */
> > -phys_addr_t __init efi_memmap_alloc(unsigned int num_entries)
> > +phys_addr_t __init efi_memmap_alloc(unsigned int num_entries, unsigned long *flags)
> >  {
> >         unsigned long size = num_entries * efi.memmap.desc_size;
> >
> > -       if (slab_is_available())
> > +       if (slab_is_available()) {
> > +               *flags |= EFI_MEMMAP_SLAB;
> >                 return __efi_memmap_alloc_late(size);
> > +       }
> >
> > +       *flags |= EFI_MEMMAP_MEMBLOCK;
>
> This assumes flags has neither bit set, but perhaps we should at least
> clear the memblock one if we set the slab one?

Ok.