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ARM: 8591/1: mm: use fully constructed struct pages for EFI pgd allocations

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The late_alloc() PTE allocation function used by create_mapping_late()
does not call pgtable_page_ctor() on PTE pages it allocates, leaving
the per-page spinlock uninitialized.

Since generic page table manipulation code may assume that translation
table pages that are not owned by init_mm are covered by fully
constructed struct pages, the following crash may occur with the new
UEFI memory attributes table code.

  efi: memattr: Processing EFI Memory Attributes table:
  efi: memattr:  0x0000ffa16000-0x0000ffa82fff [Runtime Code       |RUN|  |  |XP|  |  |  |   |  |  |  |  ]
  Unable to handle kernel NULL pointer dereference at virtual address 00000010
  pgd = c0204000
  [00000010] *pgd=00000000
  Internal error: Oops: 5 [#1] SMP ARM
  Modules linked in:
  CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.7.0-rc4-00063-g3882aa7b340b #361
  Hardware name: Generic DT based system
  task: ed858000 ti: ed842000 task.ti: ed842000
  PC is at __lock_acquire+0xa0/0x19a8
  ...
  [<c038c830>] (__lock_acquire) from [<c038e4f8>] (lock_acquire+0x6c/0x88)
  [<c038e4f8>] (lock_acquire) from [<c0c06134>] (_raw_spin_lock+0x2c/0x3c)
  [<c0c06134>] (_raw_spin_lock) from [<c0410384>] (apply_to_page_range+0xe8/0x238)
  [<c0410384>] (apply_to_page_range) from [<c1205f34>] (efi_set_mapping_permissions+0x54/0x5c)
  [<c1205f34>] (efi_set_mapping_permissions) from [<c1247474>] (efi_memattr_apply_permissions+0x2b8/0x378)
  [<c1247474>] (efi_memattr_apply_permissions) from [<c1248258>] (arm_enable_runtime_services+0x1f0/0x22c)
  [<c1248258>] (arm_enable_runtime_services) from [<c0301f0c>] (do_one_initcall+0x44/0x174)
  [<c0301f0c>] (do_one_initcall) from [<c1200d10>] (kernel_init_freeable+0x90/0x1e8)
  [<c1200d10>] (kernel_init_freeable) from [<c0bff690>] (kernel_init+0x8/0x114)
  [<c0bff690>] (kernel_init) from [<c0307ed0>] (ret_from_fork+0x14/0x24)

The crash is due to the fact that the UEFI page tables are not owned by
init_mm, but are not covered by fully constructed struct pages.

Given that the UEFI subsystem is currently the only user of
create_mapping_late(), add an unconditional call to pgtable_page_ctor() to
late_alloc().

Fixes: 9fc68b717c ("ARM/efi: Apply strict permissions for UEFI Runtime Services regions")
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Ard Biesheuvel 2016-07-28 19:48:44 +01:00 committed by Russell King
parent b9a019899f
commit 61444cde91
1 changed files with 2 additions and 1 deletions
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3
arch/arm/mm/mmu.c
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@ -728,7 +728,8 @@ static void *__init late_alloc(unsigned long sz)
{
void *ptr = (void *)__get_free_pages(PGALLOC_GFP, get_order(sz));
BUG_ON(!ptr);
if (!ptr || !pgtable_page_ctor(virt_to_page(ptr)))
BUG();
return ptr;
}