New warnings on the version 2.28.2 on ecp.c and bignum.c

[Kasimashi]

Summary

Using an EWARM compiler (IAR for Embedded Workbench ARM) , I've new warnings on MBEDTLS_MPI_CHK macro.

System information

Mbed TLS version (number or commit id): 2.28.2
Operating system and version: Windows
Configuration (if not default, please attach mbedtls_config.h):
Compiler and options (if you used a pre-built binary, please indicate how you obtained it): EWARM
Additional environment information:

Expected behavior

We should not have any warning on compilation.

Actual behavior

Issue spotted on bignum.c file.

Warning[Pe546]: transfer of control bypasses initialization of: mbedtls\library\bignum.c 2174 variable "exponent_bits_in_window" (declared at line 2183)

Same issue on ecp.c file

Steps to reproduce

Compile MbedTLS using EWARM 9.20.2

Additional information

[paul-elliott-arm]

Hi,

I have had a look at this, and I presume the complaint is from the MBEDTLS_MPI_CHK() potentially failing and jumping to the cleanup label. This seems spurious to me, as not only is the initialisation of exponent_bits_in_window skipped, its also unused in this case. The same goes for have_rng

[paul-elliott-arm]

Hi Kasimashi,

I have pushed a PR to solve these (#6929) but I cannot test this. If you could test this and report back on that PR, that would be great, as I will need to forward port this back to development as well.

[Kasimashi]

Hello @paul-elliott-arm

Thanks you very much for the feedback and for the correction : its remain some warning on ecp.c but on bignum.c it's ok.

On ecp.c you have the same issue on the function ecp_mul_comb_after_precomp

MBEDTLS_MPI_CHK is called before have_rng could you please modify that ?

Last as you can spot on the screen above there is a last warning in the function : ecp_drbg_seed, if you can also fix it (It's an old warning from previous version) maybe you have to cast it to : (mbedtls_md_type_t)

Warning[Pe188]: enumerated type mixed with another type	library\ecp.c	165	

[paul-elliott-arm]

Hi @Kasimashi - I have updated the PR, please re-review. If there are a lot more issues, and in future I invite you to submit a PR fixing the warnings, as otherwise this is very slow going!

[Kasimashi]

Thanks you !! :)

I would do that next time.

I'm not used to the process yet but it will come :)

Thanks !

All warnings are resolved with this PR.

[Kasimashi]

@paul-elliott-arm Pull Request merged this ticket can be closed.