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

Heiko Stuebner
2020-05-22T14:19:33Z

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@theobroma-systems.com>
---
changes in v4:
- new patch

lib/rsa/rsa-keyprop.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/rsa/rsa-keyprop.c b/lib/rsa/rsa-keyprop.c
index 4b54db44c4..e28fbb7472 100644
--- a/lib/rsa/rsa-keyprop.c
+++ b/lib/rsa/rsa-keyprop.c
@@ -659,8 +659,8 @@ int rsa_gen_key_prop(const void *key, uint32_t keylen, struct key_prop **prop)

*prop = calloc(sizeof(**prop), 1);
n = calloc(sizeof(uint32_t), 1 + (max_rsa_size >> 5));
- rr = calloc(sizeof(uint32_t), 1 + (max_rsa_size >> 5));
- rrtmp = calloc(sizeof(uint32_t), 1 + (max_rsa_size >> 5));
+ rr = calloc(sizeof(uint32_t), 1 + ((max_rsa_size * 2) >> 5));
+ rrtmp = calloc(sizeof(uint32_t), 1 + ((max_rsa_size * 2) >> 5));
if (!(*prop) || !n || !rr || !rrtmp) {
ret = -ENOMEM;
goto err;
--
2.25.1