Use `uint_fast8_t` instead of `unsigned char` in various loop-type
situations. This avoids the need for a 16 or 32-bit system to insert
explicit narrow-to-8-bit instructions.
Not the result of an exhaustive source analysis, rather inspecting
the disassembly output for a cut-down Cortex-M0+ build looking for
UXTB etc instructions, so there could well be more in the complete
configuration.
Signed-off-by: Kevin Bracey <kevin.bracey@arm.com>
This commits reverts to plain memset() for cases like:
some_type foo;
memset( &foo, 0, sizeof( foo ) );
(Sometimes there is code between declaration in memset(), but it doesn't
matter as long as it doesn't touch foo.)
The reasoning is the same as in the previous commit: the stack shouldn't
contain sensitive data as we carefully wipe it after use.
We call xxx_init() on a structure when it has been freshly allocated (on the
stack or heap).
At this point it contains random-looking data none of which should be
sensitive, as all sensitive data is wiped using mbedtls_platform_zeroize()
when we're done using it and the memory area is going to be reclaimed (by
exiting the function or free()ing the buffer).
Steps:
1. sed -i 's/\bmemset(\([^)]\)/mbedtls_platform_memset(\1/g' library/*.c tinycrypt/*.c include/mbedtls/*.h scripts/data_files/*.fmt
2. Manually edit library/platform_util.c to revert to memset() in the
implementations of mbedtls_platform_memset() and mbedtls_platform_memcpy()
3. egrep -n '\<memset\>' library/*.c include/mbedtls/*.h tinycrypt/*.c
The remaining occurrences are in three categories:
a. From point 2 above.
b. In comments.
c. In the initialisation of memset_func, to be changed in a future commit.
This commit improves hygiene and formatting of macro definitions
throughout the library. Specifically:
- It adds brackets around parameters to avoid unintended
interpretation of arguments, e.g. due to operator precedence.
- It adds uses of the `do { ... } while( 0 )` idiom for macros that
can be used as commands.
In `mbedtls_ccm_self_test()`, enforce input and output
buffers sent to the ccm API to be contigous and aligned,
by copying the test vectors to buffers on the stack.
This commit removes all the static occurrencies of the function
mbedtls_zeroize() in each of the individual .c modules. Instead the
function has been moved to utils.h that is included in each of the
modules.
