On 31.07.23 14:46, Ilias Apalodimas wrote:
Hi Heinrich,
On Sun, 30 Jul 2023 at 13:51, Heinrich Schuchardt
<[email protected]> wrote:
On 32bit systems (pages << EFI_PAGE_SHIFT) may lead to an overflow which
does not occur in 64bit arithmetics.
You mean this cant happen in 32 bits but can in 64bit right?
'pages << EFI_PAGE_SHIFT' can overflow both on 32bit and on 64bit.
'(u64)pages << EFI_PAGE_SHIFT' can only overflow on 64bit.
Adding (u64) is the fix for 32bit.
An overflow of (pages << EFI_PAGE_SHIFT) on 64bit systems should be treated
as an error.
Signed-off-by: Heinrich Schuchardt <[email protected]>
---
v2:
%s/size/sizeof/
lib/efi_loader/efi_memory.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/lib/efi_loader/efi_memory.c b/lib/efi_loader/efi_memory.c
index e2ca78d935..9de6cf6010 100644
--- a/lib/efi_loader/efi_memory.c
+++ b/lib/efi_loader/efi_memory.c
@@ -487,7 +487,7 @@ efi_status_t efi_allocate_pages(enum efi_allocate_type type,
enum efi_memory_type memory_type,
efi_uintn_t pages, uint64_t *memory)
{
- u64 len = pages << EFI_PAGE_SHIFT;
+ u64 len;
efi_status_t ret;
uint64_t addr;
@@ -497,6 +497,11 @@ efi_status_t efi_allocate_pages(enum efi_allocate_type
type,
return EFI_INVALID_PARAMETER;
if (!memory)
return EFI_INVALID_PARAMETER;
+ len = (u64)pages << EFI_PAGE_SHIFT;
+ /* Catch possible overflow on 64bit systems */
+ if (sizeof(efi_uintn_t) == sizeof(u64) &&
+ (len >> EFI_PAGE_SHIFT) != (u64)pages)
+ return EFI_OUT_OF_RESOURCES;
EFI_INVALID_PARAMETER is better here, since no allocation actually takes place.
The overflow occurs if a user requested more pages than fit into the
64bit address space.
According to the UEFI 2.10 EFI_OUT_OF_RESOURCES is to be used for all
cases where "The pages could not be allocated".
EFI_INVALID_PARAMETER is only foreseen for very specific exceptions.
Best regards
Heinrich
switch (type) {
case EFI_ALLOCATE_ANY_PAGES:
--
2.40.1
Regards
/Ilias
