arm64: efi: deal with NULL return value of early_memremap()

Add NULL return value checks to two invocations of early_memremap()
in the UEFI init code. For the UEFI configuration tables, we just
warn since we have a better chance of being able to report the issue
in a way that can actually be noticed by a human operator if we don't
abort right away. For the UEFI memory map, however, all we can do is
panic() since we cannot proceed without a description of memory.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Matt Fleming <matt@codeblueprint.co.uk>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 13 insertions, 1 deletions

diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
index fe7cd1afa109..96e4b1b7de46 100644
--- a/arch/arm64/kernel/efi.c
+++ b/arch/arm64/kernel/efi.c
@@ -127,7 +127,11 @@ static int __init uefi_init(void)
         table_size = sizeof(efi_config_table_64_t) * efi.systab->nr_tables;
         config_tables = early_memremap(efi_to_phys(efi.systab->tables),
                                        table_size);
-
+        if (config_tables == NULL) {
+                pr_warn("Unable to map EFI config table array.\n");
+                retval = -ENOMEM;
+                goto out;
+        }
         retval = efi_config_parse_tables(config_tables, efi.systab->nr_tables,
                                          sizeof(efi_config_table_64_t), NULL);
 
@@ -209,6 +213,14 @@ void __init efi_init(void)
                          PAGE_ALIGN(params.mmap_size + (params.mmap & ~PAGE_MASK)));
         memmap.phys_map = params.mmap;
         memmap.map = early_memremap(params.mmap, params.mmap_size);
+        if (memmap.map == NULL) {
+                /*
+                * If we are booting via UEFI, the UEFI memory map is the only
+                * description of memory we have, so there is little point in
+                * proceeding if we cannot access it.
+                */
+                panic("Unable to map EFI memory map.\n");
+        }
         memmap.map_end = memmap.map + params.mmap_size;
         memmap.desc_size = params.desc_size;
         memmap.desc_version = params.desc_ver;