efi_loader: Fix crash on 32-bit systems

A type mismatch in the efi_allocate_pool boot service flow causes
hazardous memory scribbling on 32-bit systems.

This is efi_allocate_pool's prototype:

static efi_status_t EFIAPI efi_allocate_pool(int pool_type,
						    unsigned long size,
						    void **buffer);

Internally, it invokes efi_allocate_pages as follows:

efi_allocate_pages(0, pool_type, (size + 0xfff) >> 12,
					    (void*)buffer);

This is efi_allocate_pages' prototype:

efi_status_t efi_allocate_pages(int type, int memory_type,
					unsigned long pages,
					uint64_t *memory);

The problem: efi_allocate_pages does this internally:

    *memory = addr;

This fix in efi_allocate_pool uses a transitional uintptr_t cast to
ensure the correct outcome, irrespective of the system's native word
size.

This was observed when bootefi'ing the EFI instance of FreeBSD's first
stage bootstrap (boot1.efi) on a 32-bit ARM platform (Qemu VExpress +
Cortex-a9).

Signed-off-by: Robin Randhawa <robin.randhawa@arm.com>
Signed-off-by: Alexander Graf <agraf@suse.de>

1 files changed, 3 insertions, 1 deletions

diff --git a/lib/efi_loader/efi_boottime.c b/lib/efi_loader/efi_boottime.c
index 792db39f516..a11100f4fcd 100644
--- a/lib/efi_loader/efi_boottime.c
+++ b/lib/efi_loader/efi_boottime.c
@@ -134,9 +134,11 @@ static efi_status_t EFIAPI efi_allocate_pool(int pool_type, unsigned long size,
 					     void **buffer)
 {
 	efi_status_t r;
+	efi_physical_addr_t t;
 
 	EFI_ENTRY("%d, %ld, %p", pool_type, size, buffer);
-	r = efi_allocate_pages(0, pool_type, (size + 0xfff) >> 12, (void*)buffer);
+	r = efi_allocate_pages(0, pool_type, (size + 0xfff) >> 12, &t);
+	*buffer = (void *)(uintptr_t)t;
 	return EFI_EXIT(r);
 }