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 --- lib/efi_loader/efi_boottime.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/lib/efi_loader/efi_boottime.c b/lib/efi_loader/efi_boottime.c index be6f5e8..784891b 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); }