On 4/13/19 1:31 AM, Laszlo Ersek wrote:
> RH covscan justifiedly reports that accessing "EFI_FFS_FILE_HEADER.Size"
> and "EFI_COMMON_SECTION_HEADER.Size", which both are of type UINT8[3],
> through (UINT32*), is undefined behavior:
>
>> Error: OVERRUN (CWE-119):
>> edk2-89910a39dcfd/OvmfPkg/Sec/SecMain.c:283: overrun-local: Overrunning
>> array of 3 bytes at byte offset 3 by dereferencing pointer
>> "(UINT32 *)File->Size".
>> # 281|
>> # 282| File = (EFI_FFS_FILE_HEADER*)(UINTN) CurrentAddress;
>> # 283|-> Size = *(UINT32*) File->Size & 0xffffff;
>> # 284| if (Size < (sizeof (*File) + sizeof
>> (EFI_COMMON_SECTION_HEADER))) {
>> # 285| return EFI_VOLUME_CORRUPTED;
>>
>> Error: OVERRUN (CWE-119):
>> edk2-89910a39dcfd/OvmfPkg/Sec/SecMain.c:614: overrun-local: Overrunning
>> array of 3 bytes at byte offset 3 by dereferencing pointer
>> "(UINT32 *)File->Size".
>> # 612|
>> # 613| File = (EFI_FFS_FILE_HEADER*)(UINTN) CurrentAddress;
>> # 614|-> Size = *(UINT32*) File->Size & 0xffffff;
>> # 615| if (Size < sizeof (*File)) {
>> # 616| return EFI_NOT_FOUND;
>>
>> Error: OVERRUN (CWE-119):
>> edk2-89910a39dcfd/OvmfPkg/Sec/SecMain.c:639: overrun-local: Overrunning
>> array of 3 bytes at byte offset 3 by dereferencing pointer
>> "(UINT32 *)Section->Size".
>> # 637| Section = (EFI_COMMON_SECTION_HEADER*)(UINTN) CurrentAddress;
>> # 638|
>> # 639|-> Size = *(UINT32*) Section->Size & 0xffffff;
>> # 640| if (Size < sizeof (*Section)) {
>> # 641| return EFI_NOT_FOUND;
>
> Fix these by invoking the FFS_FILE_SIZE() and SECTION_SIZE() macros, which
> by now have been fixed too.
>
> Cc: Ard Biesheuvel <[email protected]>
> Cc: Jordan Justen <[email protected]>
> Bugzilla: https://bugzilla.tianocore.org/show_bug.cgi?id=1710
> Issue: scan-1008.txt
> Issue: scan-1009.txt
> Issue: scan-1010.txt
> Signed-off-by: Laszlo Ersek <[email protected]>
> ---
> OvmfPkg/Sec/SecMain.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/OvmfPkg/Sec/SecMain.c b/OvmfPkg/Sec/SecMain.c
> index 18a89c649fd4..3914355cd17b 100644
> --- a/OvmfPkg/Sec/SecMain.c
> +++ b/OvmfPkg/Sec/SecMain.c
> @@ -269,17 +269,17 @@ FindFfsFileAndSection (
> for (EndOfFile = CurrentAddress + Fv->HeaderLength; ; ) {
>
> CurrentAddress = (EndOfFile + 7) & ~(7ULL);
> if (CurrentAddress > EndOfFirmwareVolume) {
> return EFI_VOLUME_CORRUPTED;
> }
>
> File = (EFI_FFS_FILE_HEADER*)(UINTN) CurrentAddress;
> - Size = *(UINT32*) File->Size & 0xffffff;
> + Size = FFS_FILE_SIZE (File);
> if (Size < (sizeof (*File) + sizeof (EFI_COMMON_SECTION_HEADER))) {
> return EFI_VOLUME_CORRUPTED;
> }
>
> EndOfFile = CurrentAddress + Size;
> if (EndOfFile > EndOfFirmwareVolume) {
> return EFI_VOLUME_CORRUPTED;
> }
> @@ -600,17 +600,17 @@ FindImageBase (
> for (EndOfFile = CurrentAddress + BootFirmwareVolumePtr->HeaderLength; ; )
> {
>
> CurrentAddress = (EndOfFile + 7) & 0xfffffffffffffff8ULL;
> if (CurrentAddress > EndOfFirmwareVolume) {
> return EFI_NOT_FOUND;
> }
>
> File = (EFI_FFS_FILE_HEADER*)(UINTN) CurrentAddress;
> - Size = *(UINT32*) File->Size & 0xffffff;
> + Size = FFS_FILE_SIZE (File);
> if (Size < sizeof (*File)) {
> return EFI_NOT_FOUND;
> }
>
> EndOfFile = CurrentAddress + Size;
> if (EndOfFile > EndOfFirmwareVolume) {
> return EFI_NOT_FOUND;
> }
> @@ -625,17 +625,17 @@ FindImageBase (
> //
> // Loop through the FFS file sections within the FFS file
> //
> EndOfSection = (EFI_PHYSICAL_ADDRESS)(UINTN) (File + 1);
> for (;;) {
> CurrentAddress = (EndOfSection + 3) & 0xfffffffffffffffcULL;
> Section = (EFI_COMMON_SECTION_HEADER*)(UINTN) CurrentAddress;
>
> - Size = *(UINT32*) Section->Size & 0xffffff;
> + Size = SECTION_SIZE (Section);
> if (Size < sizeof (*Section)) {
> return EFI_NOT_FOUND;
> }
>
> EndOfSection = CurrentAddress + Size;
> if (EndOfSection > EndOfFile) {
> return EFI_NOT_FOUND;
> }
>
Reviewed-by: Philippe Mathieu-Daude <[email protected]>
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