Compile error with SPL_FIT_FULL_CHECK and SPL_LOAD_FIT_FULL enabled

[Philippe REYNES]

Hi Johann,

Le 08/02/2022 à 16:43, Johann Neuhauser a écrit :
> Dear developers and Simon,
>
> we wanna run secure boot with U-Boot's SPL_FIT_SIGNATURE and FIT_SIGNATURE on our STM32MP1 boards and discovered the CVE-2021-27097.
> To mitigate this vulnerability we wanna enable SPL_LOAD_FIT_FULL and SPL_FIT_FULL_CHECK.
> If I compile any U-Boot SPL with the mentioned config symbols after commit 6f3c2d8a, it fails always with the following error message:
>
> Used defconfig: stm32mp15_dhcom_basic_defconfig (+ mentioned configs enabled)
> ```
> ...
>    LD      spl/lib/built-in.o
>    LD      spl/u-boot-spl
> /usr/bin/arm-linux-gnueabihf-ld.bfd: common/built-in.o: in function `fit_check_format':
> /mnt/work/dev/u-boot/common/image-fit.c:1591: undefined reference to `fdt_check_full'
> make[1]: *** [scripts/Makefile.spl:432: spl/u-boot-spl] Error 1
> make: *** [Makefile:1941: spl/u-boot-spl] Error 2
> ```
> After diging around to find the cause, we're out of ideas.
> Does anyone have a clue why the needed function is not compiled in libfdt for the spl build?
I have reproduced this issue with this config 
(stm32mp15_dhcom_basic_defconfig (+ mentioned configs enabled)).
The function fdt_check_full is build conditionnaly:

#if !defined(FDT_ASSUME_MASK) || FDT_ASSUME_MASK != 0xff
int fdt_check_full(const void *fdt, size_t bufsize)

{

...

}

In this config FDT_ASSUME_MASK is 0xff, so the function fdt_check_full 
is not compiled.
I succeed to build (not tested) with this patch:

--- a/scripts/dtc/libfdt/fdt_ro.c
+++ b/scripts/dtc/libfdt/fdt_ro.c
@@ -937,4 +937,9 @@ int fdt_check_full(const void *fdt, size_t bufsize)
                 }
         }
  }
+#else
+int fdt_check_full(const void *fdt, size_t bufsize)
+{
+       return 0;
+}
  #endif


If simon agrees with this fix, I may sent a patch.

>
> Many thanks in advance.
>
> Best regards,
>
> Johann Neuhauser
>
> DH electronics GmbH | Am Anger 8 | 83346 Bergen | Germany | Fon: +49 8662 4882 0
> Board of Management: Stefan Daxenberger, Helmut Henschke | HRB Traunstein 9602


Regards,
Philippe