[PATCH 0/4] fit: Harden handling of external-data properties

The data-offset, data-position and data-size FIT properties are 32-bit
unsigned values, but were read through signed int. Also, they are
excluded from the configuration signature, so they are attacker
controlled.

Patch 1 switches the accessors and their callers to u32, removing
the ad-hoc handling of "negative" values in U-Boot proper. This
transition was discussed and agreed on in [1].

The SPL loader has its own copy of this logic with the same problems
and fewer checks. Patch 2 factors out a test helper, patch 3 makes the
SPL offset/size arithmetic overflow-safe, and patch 4 adds the
addressable-range and FIT_SIGNATURE_MAX_SIZE bounds check that U-Boot
proper already performs in fit_image_get_data().

Patches 3 and 4 build on each other and on patch 1, so they are not
intended to be cherry-picked individually.

[1] https://lore.kernel.org/u-boot/CAPWaX55XWFLcMGRuaUuXXn__MX_UG4J8QTd6rvXZmJ4WSOCy9w@mail.gmail.com/

---
Anton Ivanov (4):
      image-fit: Use unsigned types for external data properties
      test: spl: Factor out external-data FIT property checks
      spl: fit: Harden external-data offset and size arithmetic
      spl: fit: Bound external data like U-Boot proper

 boot/image-fit.c               |  29 ++++------
 common/spl/spl_fit.c           | 122 +++++++++++++++++++++++++--------------
 common/splash_source.c         |   2 +-
 drivers/fpga/socfpga_arria10.c |   3 +-
 include/image.h                |   6 +-
 test/image/spl_load.c          | 128 +++++++++++++++++++++++++++++++++++------
 test/py/tests/test_vboot.py    |   6 +-
 7 files changed, 206 insertions(+), 90 deletions(-)
---
base-commit: 94b349bd902d9e38e1846c157fadd9054c34680a
change-id: 20260730-b4-fit-ext-data-hardening-1734a9203753

Best regards,
--  
Anton Ivanov <[email protected]>