[PATCH 3.16 299/366] efi: Avoid potential crashes, fix the 'struct efi_pci_io_protocol_32' definition for mixed mode

[Ben Hutchings]

3.16.60-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>

commit 0b3225ab9407f557a8e20f23f37aa7236c10a9b1 upstream.

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@xxxxxxxxxx>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: linux-efi@xxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/20180504060003.19618-13-ard.biesheuvel@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 arch/x86/boot/compressed/eboot.c | 6 ++++--
 include/linux/efi.h              | 8 ++++----
 2 files changed, 8 insertions(+), 6 deletions(-)

--- a/arch/x86/boot/compressed/eboot.c
+++ b/arch/x86/boot/compressed/eboot.c
@@ -358,7 +358,8 @@ __setup_efi_pci32(efi_pci_io_protocol_32
 	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:
@@ -460,7 +461,8 @@ __setup_efi_pci64(efi_pci_io_protocol_64
 	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:
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -368,8 +368,8 @@ 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 {
@@ -388,8 +388,8 @@ 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 {