Merge remote-tracking branch 'origin/pr/2700' into mbedtls-2.16
* origin/pr/2700:
Changelog entry for HAVEGE fix
Prevent building the HAVEGE module on platforms where it doesn't work
Fix misuse of signed ints in the HAVEGE module
diff --git a/ChangeLog b/ChangeLog
index 9702af2..01da443 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -12,6 +12,7 @@
irwir.
* Enable Suite B with subset of ECP curves. Make sure the code compiles even
if some curves are not defined. Fixes #1591 reported by dbedev.
+ * Fix misuse of signed arithmetic in the HAVEGE module. #2598
Changes
* Make it easier to define MBEDTLS_PARAM_FAILED as assert (which config.h
diff --git a/library/havege.c b/library/havege.c
index 54f897c..c139e1d 100644
--- a/library/havege.c
+++ b/library/havege.c
@@ -38,8 +38,19 @@
#include "mbedtls/timing.h"
#include "mbedtls/platform_util.h"
+#include <limits.h>
#include <string.h>
+/* If int isn't capable of storing 2^32 distinct values, the code of this
+ * module may cause a processor trap or a miscalculation. If int is more
+ * than 32 bits, the code may not calculate the intended values. */
+#if INT_MIN + 1 != -0x7fffffff
+#error "The HAVEGE module requires int to be exactly 32 bits, with INT_MIN = -2^31."
+#endif
+#if UINT_MAX != 0xffffffff
+#error "The HAVEGE module requires unsigned to be exactly 32 bits."
+#endif
+
/* ------------------------------------------------------------------------
* On average, one iteration accesses two 8-word blocks in the havege WALK
* table, and generates 16 words in the RES array.
@@ -54,7 +65,7 @@
* ------------------------------------------------------------------------
*/
-#define SWAP(X,Y) { int *T = (X); (X) = (Y); (Y) = T; }
+#define SWAP(X,Y) { unsigned *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 +88,7 @@
PTX = (PT1 >> 18) & 7; \
PT1 &= 0x1FFF; \
PT2 &= 0x1FFF; \
- CLK = (int) mbedtls_timing_hardclock(); \
+ CLK = (unsigned) mbedtls_timing_hardclock(); \
\
i = 0; \
A = &WALK[PT1 ]; RES[i++] ^= *A; \
@@ -100,7 +111,7 @@
\
IN = (*A >> (5)) ^ (*A << (27)) ^ CLK; \
*A = (*B >> (6)) ^ (*B << (26)) ^ CLK; \
- *B = IN; CLK = (int) mbedtls_timing_hardclock(); \
+ *B = IN; CLK = (unsigned) mbedtls_timing_hardclock(); \
*C = (*C >> (7)) ^ (*C << (25)) ^ CLK; \
*D = (*D >> (8)) ^ (*D << (24)) ^ CLK; \
\
@@ -151,19 +162,20 @@
PT1 ^= (PT2 ^ 0x10) & 0x10; \
\
for( n++, i = 0; i < 16; i++ ) \
- hs->pool[n % MBEDTLS_HAVEGE_COLLECT_SIZE] ^= RES[i];
+ POOL[n % MBEDTLS_HAVEGE_COLLECT_SIZE] ^= RES[i];
/*
* Entropy gathering function
*/
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;
+ unsigned i, n = 0;
+ unsigned U1, U2, *A, *B, *C, *D;
+ unsigned PT1, PT2, *WALK, *POOL, RES[16];
+ unsigned PTX, PTY, CLK, PTEST, IN;
- WALK = hs->WALK;
+ WALK = (unsigned *) hs->WALK;
+ POOL = (unsigned *) hs->pool;
PT1 = hs->PT1;
PT2 = hs->PT2;