More robust code to set the IV
Check that the source address and the frame counter have the expected
length. Otherwise, if the test data was invalid, the test code could
build nonsensical inputs, potentially overflowing the iv buffer.
The primary benefit of this change is that it also silences a warning
from compiling with `gcc-10 -O3` (observed with GCC 10.2.0 on
Linux/amd64). GCC unrolled the loops and complained about a buffer
overflow with warnings like:
```
suites/test_suite_ccm.function: In function 'test_mbedtls_ccm_star_auth_decrypt':
suites/test_suite_ccm.function:271:15: error: writing 1 byte into a region of size 0 [-Werror=stringop-overflow=]
271 | iv[i] = source_address->x[i];
| ~~~~~~^~~~~~~~~~~~~~~~~~~~~~
suites/test_suite_ccm.function:254:19: note: at offset [13, 14] to object 'iv' with size 13 declared here
254 | unsigned char iv[13];
```
Just using memcpy instead of loops bypasses this warnings. The added
checks are a bonus.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/suites/test_suite_ccm.function b/tests/suites/test_suite_ccm.function
index faa7e13..5a3726e 100644
--- a/tests/suites/test_suite_ccm.function
+++ b/tests/suites/test_suite_ccm.function
@@ -201,12 +201,11 @@
unsigned char iv[13];
unsigned char result[50];
mbedtls_ccm_context ctx;
- size_t i, iv_len, tag_len;
+ size_t iv_len, tag_len;
int ret;
mbedtls_ccm_init( &ctx );
- memset( iv, 0x00, sizeof( iv ) );
memset( result, 0x00, sizeof( result ) );
if( sec_level % 4 == 0)
@@ -214,12 +213,10 @@
else
tag_len = 1 << ( sec_level % 4 + 1);
- for( i = 0; i < source_address->len; i++ )
- iv[i] = source_address->x[i];
-
- for( i = 0; i < frame_counter->len; i++ )
- iv[source_address->len + i] = frame_counter->x[i];
-
+ TEST_ASSERT( source_address->len == 8 );
+ TEST_ASSERT( frame_counter->len == 4 );
+ memcpy( iv, source_address->x, source_address->len );
+ memcpy( iv + source_address->len, frame_counter->x, frame_counter->len );
iv[source_address->len + frame_counter->len] = sec_level;
iv_len = sizeof( iv );
@@ -254,7 +251,7 @@
unsigned char iv[13];
unsigned char result[50];
mbedtls_ccm_context ctx;
- size_t i, iv_len, tag_len;
+ size_t iv_len, tag_len;
int ret;
mbedtls_ccm_init( &ctx );
@@ -267,12 +264,10 @@
else
tag_len = 1 << ( sec_level % 4 + 1);
- for( i = 0; i < source_address->len; i++ )
- iv[i] = source_address->x[i];
-
- for( i = 0; i < frame_counter->len; i++ )
- iv[source_address->len + i] = frame_counter->x[i];
-
+ TEST_ASSERT( source_address->len == 8 );
+ TEST_ASSERT( frame_counter->len == 4 );
+ memcpy( iv, source_address->x, source_address->len );
+ memcpy( iv + source_address->len, frame_counter->x, frame_counter->len );
iv[source_address->len + frame_counter->len] = sec_level;
iv_len = sizeof( iv );
