efi: Avoid potential crashes, fix the 'struct efi_pci_io_protocol_32' definition for mixed mode

Mixed mode allows a kernel built for x86_64 to interact with 32-bit
EFI firmware, but requires us to define all struct definitions carefully
when it comes to pointer sizes.

'struct efi_pci_io_protocol_32' currently uses a 'void *' for the
'romimage' field, which will be interpreted as a 64-bit field
on such kernels, potentially resulting in bogus memory references
and subsequent crashes.

Tested-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: <stable@vger.kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20180504060003.19618-13-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

2 files changed, 8 insertions, 6 deletions

diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
index 47d3efff6805..09f36c0d9d4f 100644
--- a/arch/x86/boot/compressed/eboot.c
+++ b/arch/x86/boot/compressed/eboot.c
@@ -163,7 +163,8 @@ __setup_efi_pci32(efi_pci_io_protocol_32 *pci, struct pci_setup_rom **__rom)
         if (status != EFI_SUCCESS)
                 goto free_struct;
 
-        memcpy(rom->romdata, pci->romimage, pci->romsize);
+        memcpy(rom->romdata, (void *)(unsigned long)pci->romimage,
+               pci->romsize);
         return status;
 
 free_struct:
@@ -269,7 +270,8 @@ __setup_efi_pci64(efi_pci_io_protocol_64 *pci, struct pci_setup_rom **__rom)
         if (status != EFI_SUCCESS)
                 goto free_struct;
 
-        memcpy(rom->romdata, pci->romimage, pci->romsize);
+        memcpy(rom->romdata, (void *)(unsigned long)pci->romimage,
+               pci->romsize);
         return status;
 
 free_struct:
diff --git a/include/linux/efi.h b/include/linux/efi.h
index f1b7d68ac460..3016d8c456bc 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -395,8 +395,8 @@ typedef struct {
         u32 attributes;
         u32 get_bar_attributes;
         u32 set_bar_attributes;
-        uint64_t romsize;
-        void *romimage;
+        u64 romsize;
+        u32 romimage;
 } efi_pci_io_protocol_32;
 
 typedef struct {
@@ -415,8 +415,8 @@ typedef struct {
         u64 attributes;
         u64 get_bar_attributes;
         u64 set_bar_attributes;
-        uint64_t romsize;
-        void *romimage;
+        u64 romsize;
+        u64 romimage;
 } efi_pci_io_protocol_64;
 
 typedef struct {