efi/x86: Free efi_pgd with free_pages()

Commit

  d9e9a6418065 ("x86/mm/pti: Allocate a separate user PGD")

changed the PGD allocation to allocate PGD_ALLOCATION_ORDER pages, so in
the error path it should be freed using free_pages() rather than
free_page().

Commit

    06ace26f4e6f ("x86/efi: Free efi_pgd with free_pages()")

fixed one instance of this, but missed another.

Move the freeing out-of-line to avoid code duplication and fix this bug.

Fixes: d9e9a6418065 ("x86/mm/pti: Allocate a separate user PGD")
Link: https://lore.kernel.org/r/20201110163919.1134431-1-nivedita@alum.mit.edu
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index 8f5759d..e1e8d4e 100644 (file)
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -78,28 +78,30 @@ int __init efi_alloc_page_tables(void)
        gfp_mask = GFP_KERNEL | __GFP_ZERO;
        efi_pgd = (pgd_t *)__get_free_pages(gfp_mask, PGD_ALLOCATION_ORDER);
        if (!efi_pgd)
-               return -ENOMEM;
+               goto fail;
 
        pgd = efi_pgd + pgd_index(EFI_VA_END);
        p4d = p4d_alloc(&init_mm, pgd, EFI_VA_END);
-       if (!p4d) {
-               free_page((unsigned long)efi_pgd);
-               return -ENOMEM;
-       }
+       if (!p4d)
+               goto free_pgd;
 
        pud = pud_alloc(&init_mm, p4d, EFI_VA_END);
-       if (!pud) {
-               if (pgtable_l5_enabled())
-                       free_page((unsigned long) pgd_page_vaddr(*pgd));
-               free_pages((unsigned long)efi_pgd, PGD_ALLOCATION_ORDER);
-               return -ENOMEM;
-       }
+       if (!pud)
+               goto free_p4d;
 
        efi_mm.pgd = efi_pgd;
        mm_init_cpumask(&efi_mm);
        init_new_context(NULL, &efi_mm);
 
        return 0;
+
+free_p4d:
+       if (pgtable_l5_enabled())
+               free_page((unsigned long)pgd_page_vaddr(*pgd));
+free_pgd:
+       free_pages((unsigned long)efi_pgd, PGD_ALLOCATION_ORDER);
+fail:
+       return -ENOMEM;
 }
 
 /*