From 36168d2942b82c351daf00cd3e2744ebb10add13 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Niels=20M=C3=B6ller?= <nisse@lysator.liu.se>
Date: Mon, 19 Feb 2018 19:23:40 +0100
Subject: [PATCH] New macros TMP_DECL_ALIGN and TMP_ALLOC_ALIGN.
---
ChangeLog | 12 ++++++++++++
nettle-internal.h | 25 +++++++++++++++++++++++--
pss-mgf1.c | 4 ++--
pss.c | 8 ++++----
4 files changed, 41 insertions(+), 8 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index e354cdde..11d31bc7 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,15 @@
+2018-02-19 Niels Möller <nisse@lysator.liu.se>
+
+ * nettle-internal.h: Include sha3.h, needed for the definition of
+ NETTLE_MAX_HASH_CONTEXT_SIZE.
+ (TMP_DECL_ALIGN, TMP_ALLOC_ALIGN): New macros, to support
+ allocation of context structs with alignment requirements.
+ [!HAVE_ALLOCA]: Also use assert, rather than calling abort
+ directly.
+
+ * pss.c (pss_encode_mgf1, pss_verify_mgf1): Use new macros.
+ * pss-mgf1.c (pss_mgf1): Likewise.
+
2018-02-18 Niels Möller <nisse@lysator.liu.se>
* testsuite/Makefile.in (TS_NETTLE_SOURCES): Moved pss-mgf1-test.c...
diff --git a/nettle-internal.h b/nettle-internal.h
index 38c8d2a8..dbd989b7 100644
--- a/nettle-internal.h
+++ b/nettle-internal.h
@@ -35,20 +35,41 @@
#ifndef NETTLE_INTERNAL_H_INCLUDED
#define NETTLE_INTERNAL_H_INCLUDED
+#include <assert.h>
+
#include "nettle-meta.h"
+/* For definition of NETTLE_MAX_HASH_CONTEXT_SIZE. */
+#include "sha3.h"
+
/* Temporary allocation, for systems that don't support alloca. Note
* that the allocation requests should always be reasonably small, so
* that they can fit on the stack. For non-alloca systems, we use a
- * fix maximum size, and abort if we ever need anything larger. */
+ * fix maximum size + an assert.
+ *
+ * TMP_DECL and TMP_ALLOC allocate an array of the given type, and
+ * take the array size (not byte size) as argument.
+ *
+ * TMP_DECL_ALIGN and TMP_ALLOC_ALIGN are intended for context
+ * structs, which need proper alignment. They take the size in bytes,
+ * and produce a void *. On systems without alloca, implemented as an
+ * array of uint64_t, to ensure alignment. Since it is used as void *
+ * argument, no type casts are needed.
+ */
#if HAVE_ALLOCA
# define TMP_DECL(name, type, max) type *name
# define TMP_ALLOC(name, size) (name = alloca(sizeof (*name) * (size)))
+# define TMP_DECL_ALIGN(name, max) void *name
+# define TMP_ALLOC_ALIGN(name, size) (name = alloca(size))
#else /* !HAVE_ALLOCA */
# define TMP_DECL(name, type, max) type name[max]
# define TMP_ALLOC(name, size) \
- do { if ((size) > (sizeof(name) / sizeof(name[0]))) abort(); } while (0)
+ do { assert((size_t)(size) <= (sizeof(name) / sizeof(name[0]))); } while (0)
+# define TMP_DECL_ALIGN(name, max) \
+ uint64_t name[((max) + (sizeof(uint64_t) - 1))/ sizeof(uint64_t)]
+# define TMP_ALLOC_ALIGN(name, size) \
+ do { assert((size_t)(size) <= (sizeof(name))); } while (0)
#endif
/* Arbitrary limits which apply to systems that don't have alloca */
diff --git a/pss-mgf1.c b/pss-mgf1.c
index 67df5570..3f5e204b 100644
--- a/pss-mgf1.c
+++ b/pss-mgf1.c
@@ -48,12 +48,12 @@ pss_mgf1(const void *seed, const struct nettle_hash *hash,
size_t length, uint8_t *mask)
{
TMP_DECL(h, uint8_t, NETTLE_MAX_HASH_DIGEST_SIZE);
- TMP_DECL(state, uint8_t, NETTLE_MAX_HASH_CONTEXT_SIZE);
+ TMP_DECL_ALIGN(state, NETTLE_MAX_HASH_CONTEXT_SIZE);
size_t i;
uint8_t c[4];
TMP_ALLOC(h, hash->digest_size);
- TMP_ALLOC(state, hash->context_size);
+ TMP_ALLOC_ALIGN(state, hash->context_size);
for (i = 0;;
i++, mask += hash->digest_size, length -= hash->digest_size)
diff --git a/pss.c b/pss.c
index 88125c06..d28e7b13 100644
--- a/pss.c
+++ b/pss.c
@@ -67,12 +67,12 @@ pss_encode_mgf1(mpz_t m, size_t bits,
const uint8_t *digest)
{
TMP_GMP_DECL(em, uint8_t);
- TMP_DECL(state, uint8_t, NETTLE_MAX_HASH_CONTEXT_SIZE);
+ TMP_DECL_ALIGN(state, NETTLE_MAX_HASH_CONTEXT_SIZE);
size_t key_size = (bits + 7) / 8;
size_t j;
TMP_GMP_ALLOC(em, key_size);
- TMP_ALLOC(state, hash->context_size);
+ TMP_ALLOC_ALIGN(state, hash->context_size);
if (key_size < hash->digest_size + salt_length + 2)
{
@@ -127,7 +127,7 @@ pss_verify_mgf1(const mpz_t m, size_t bits,
{
TMP_GMP_DECL(em, uint8_t);
TMP_DECL(h2, uint8_t, NETTLE_MAX_HASH_DIGEST_SIZE);
- TMP_DECL(state, uint8_t, NETTLE_MAX_HASH_CONTEXT_SIZE);
+ TMP_DECL_ALIGN(state, NETTLE_MAX_HASH_CONTEXT_SIZE);
uint8_t *h, *db, *salt;
size_t key_size = (bits + 7) / 8;
size_t j;
@@ -138,7 +138,7 @@ pss_verify_mgf1(const mpz_t m, size_t bits,
TMP_GMP_ALLOC(em, key_size * 2);
TMP_ALLOC(h2, hash->digest_size);
- TMP_ALLOC(state, hash->context_size);
+ TMP_ALLOC_ALIGN(state, hash->context_size);
if (key_size < hash->digest_size + salt_length + 2)
goto cleanup;
--
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