[PATCH v5 4/8] lib: rsa: fix allocated size for rr and rrtmp in rsa_gen_key_prop()

[Philipp Tomsich]

> On 22.05.2020, at 16:19, Heiko Stuebner <heiko at sntech.de> wrote:
> 
> From: Heiko Stuebner <heiko.stuebner at theobroma-systems.com>
> 
> When calculating rrtmp/rr rsa_gen_key_prop() tries to make
> (((rlen + 31) >> 5) + 1) steps in the rr uint32_t array and
> (((rlen + 7) >> 3) + 1) / 4 steps in uint32_t rrtmp[]
> with rlen being num_bits * 2
> 
> On a 4096bit key this comes down to to 257 uint32_t elements
> in rr and 256 elements in rrtmp but with the current allocation
> rr and rrtmp only have 129 uint32_t elements.
> 
> On 2048bit keys this works by chance as the defined max_rsa_size=4096
> allocates a suitable number of elements, but with an actual 4096bit key
> this results in other memory parts getting overwritten.
> 
> so double the number of elements in rr and rrtmp so that it matches
> the needed number and should increase nicely if max_rsa_size gets
> increased in the future.
> 
> Signed-off-by: Heiko Stuebner <heiko.stuebner at theobroma-systems.com>

Reviewed-by: Philipp Tomsich <philipp.tomsich at theobroma-systems.com>