32 Byte key derivation may fail with a 16 Byte ROT key

[yossi2le]

Description

When trying to derive 32 bytes key with a 16 bytes ROT key the process may fail cause the ROT returned buffer size from kvstore has been ignored.

This bug fix is influencing PR #10493 (STM32F303RE: Activate FLASHIAP) because the device key test is failing on that PR.

Pull request type

[x] Fix
[ ] Refactor
[ ] Target update
[ ] Functionality change
[ ] Docs update
[ ] Test update
[ ] Breaking change

Reviewers

@JanneKiiskila, @jeromecoutant

Release Notes

[yossi2le]

@jeromecoutant, sorry to bother you but please take a look again cause I thought about it and find out the real correction is a bit different and therefore I have updated the file.

[ciarmcom]

@yossi2le, thank you for your changes.
@JanneKiiskila @ARMmbed/mbed-os-storage @ARMmbed/mbed-os-maintainers please review.

[davidsaada]

LGTM.

[adbridge]

ci started

[mbed-ci]

Test run: SUCCESS

Summary: 11 of 11 test jobs passed
Build number : 1
Build artifacts

[JanneKiiskila]

At least it now matches the function parameter defined in:

mbed-os/features/storage/kvstore/tdbstore/TDBStore.cpp

Line 1437 in 84f01d3

int TDBStore::reserved_data_get(void *reserved_data, size_t reserved_data_buf_size, size_t *actual_data_size)

Though I'm still wondering a bit which function it used before? Do we have an overloaded version somewhere, which does not have the last size_t *actual_size as parameter at all?

[yossi2le]

The actual_size parameter has a default value of 0 and therefore no overload function is needed.
You can see it at the function declaration in the header file.

[JanneKiiskila]

Found it now, yep makes sense.

[JanneKiiskila]

@adbridge @0xc0170 - target to next patch release, please.

[0xc0170]

This bug fix is influencing PR #10493 (STM32F303RE: Activate FLASHIAP) because the device key test is failing on that PR.

Also in , both will be in 5.12.3