Fix misuse of signed ints in the HAVEGE module
The elements of the HAVEGE state are manipulated with bitwise
operations, with the expectations that the elements are 32-bit
unsigned integers (or larger). But they are declared as int, and so
the code has undefined behavior. Clang with Asan correctly points out
some shifts that reach the sign bit.
Since these are supposed to be 32-bit unsigned integers, declare them
as uint32_t.
This is technically an API break, since the type mbedtls_havege_state
is exposed in a public header. However normal applications should not
be affected.
diff --git a/library/havege.c b/library/havege.c
index 54f897c..a9dded1 100644
--- a/library/havege.c
+++ b/library/havege.c
@@ -38,6 +38,7 @@
#include "mbedtls/timing.h"
#include "mbedtls/platform_util.h"
+#include <stdint.h>
#include <string.h>
/* ------------------------------------------------------------------------
@@ -54,7 +55,7 @@
* ------------------------------------------------------------------------
*/
-#define SWAP(X,Y) { int *T = (X); (X) = (Y); (Y) = T; }
+#define SWAP(X,Y) { uint32_t *T = (X); (X) = (Y); (Y) = T; }
#define TST1_ENTER if( PTEST & 1 ) { PTEST ^= 3; PTEST >>= 1;
#define TST2_ENTER if( PTEST & 1 ) { PTEST ^= 3; PTEST >>= 1;
@@ -77,7 +78,7 @@
PTX = (PT1 >> 18) & 7; \
PT1 &= 0x1FFF; \
PT2 &= 0x1FFF; \
- CLK = (int) mbedtls_timing_hardclock(); \
+ CLK = (uint32_t) mbedtls_timing_hardclock(); \
\
i = 0; \
A = &WALK[PT1 ]; RES[i++] ^= *A; \
@@ -100,7 +101,7 @@
\
IN = (*A >> (5)) ^ (*A << (27)) ^ CLK; \
*A = (*B >> (6)) ^ (*B << (26)) ^ CLK; \
- *B = IN; CLK = (int) mbedtls_timing_hardclock(); \
+ *B = IN; CLK = (uint32_t) mbedtls_timing_hardclock(); \
*C = (*C >> (7)) ^ (*C << (25)) ^ CLK; \
*D = (*D >> (8)) ^ (*D << (24)) ^ CLK; \
\
@@ -158,10 +159,11 @@
*/
static void havege_fill( mbedtls_havege_state *hs )
{
- int i, n = 0;
- int U1, U2, *A, *B, *C, *D;
- int PT1, PT2, *WALK, RES[16];
- int PTX, PTY, CLK, PTEST, IN;
+ size_t n = 0;
+ unsigned i;
+ uint32_t U1, U2, *A, *B, *C, *D;
+ uint32_t PT1, PT2, *WALK, RES[16];
+ uint32_t PTX, PTY, CLK, PTEST, IN;
WALK = hs->WALK;
PT1 = hs->PT1;
@@ -212,7 +214,7 @@
*/
int mbedtls_havege_random( void *p_rng, unsigned char *buf, size_t len )
{
- int val;
+ uint32_t val;
size_t use_len;
mbedtls_havege_state *hs = (mbedtls_havege_state *) p_rng;
unsigned char *p = buf;
@@ -220,8 +222,8 @@
while( len > 0 )
{
use_len = len;
- if( use_len > sizeof(int) )
- use_len = sizeof(int);
+ if( use_len > sizeof( val ) )
+ use_len = sizeof( val );
if( hs->offset[1] >= MBEDTLS_HAVEGE_COLLECT_SIZE )
havege_fill( hs );