From: Niels Möller <nisse@lysator.liu.se>
Date: Fri, 8 Mar 2024 16:52:51 +0000 (+0100)
Subject: Fix ubsan issue in hash update functions.
X-Git-Tag: nettle_3.10rc1~28
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=99e62003c3916fdef04a2d3327281f8f498b609e;p=thirdparty%2Fnettle.git

Fix ubsan issue in hash update functions.
---

diff --git a/ChangeLog b/ChangeLog
index 69df1d18..4fa4a72f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,14 @@
+2024-03-08  Niels Möller  <nisse@lysator.liu.se>
+
+	Fix ubsan issues for empty hash updates.
+	* macros.h (MD_UPDATE): Check upfront if length is zero. Avoids
+	calling memcpy(dst, NULL, 0), which is undefined behavior.
+	* sha256.c (sha256_update): Likewise.
+	* sha3.c (_nettle_sha3_update): Likewise.
+	* testsuite/testutils.c (test_hash): Test with message split into
+	two pieces in different ways, and also add an call to update(ctx,
+	0, NULL) in the middle.
+
 2024-02-16  Niels Möller  <nisse@lysator.liu.se>
 
 	RSA-OAEP support contributed by Nicolas Mora and Daiki Ueno:
diff --git a/macros.h b/macros.h
index 990d32ee..320f61ce 100644
--- a/macros.h
+++ b/macros.h
@@ -180,6 +180,7 @@ do {						\
    length and data. */
 #define MD_UPDATE(ctx, length, data, f, incr)				\
   do {									\
+    if (!length) goto __md_done;					\
     if ((ctx)->index)							\
       {									\
 	/* Try to fill partial block */					\
diff --git a/sha256.c b/sha256.c
index 0c9c21a0..44551224 100644
--- a/sha256.c
+++ b/sha256.c
@@ -105,6 +105,9 @@ sha256_update(struct sha256_ctx *ctx,
 	      size_t length, const uint8_t *data)
 {
   size_t blocks;
+  if (!length)
+    return;
+
   if (ctx->index > 0)
     {
       /* Try to fill partial block */
diff --git a/sha3.c b/sha3.c
index cd22041b..0eecfb22 100644
--- a/sha3.c
+++ b/sha3.c
@@ -67,6 +67,9 @@ _nettle_sha3_update (struct sha3_state *state,
 		     unsigned pos,
 		     size_t length, const uint8_t *data)
 {
+  if (!length)
+    return pos;
+
   if (pos > 0)
     {
       unsigned left = block_size - pos;
diff --git a/testsuite/testutils.c b/testsuite/testutils.c
index 6fc8a8b8..ac9d8f63 100644
--- a/testsuite/testutils.c
+++ b/testsuite/testutils.c
@@ -1108,16 +1108,22 @@ test_hash(const struct nettle_hash *hash,
     ASSERT (digest->length == hash->digest_size);
 
   hash->init(ctx);
-  hash->update(ctx, msg->length, msg->data);
-  hash->digest(ctx, digest->length, buffer);
-
-  if (MEMEQ(digest->length, digest->data, buffer) == 0)
+  for (offset = 0; offset <= msg->length && offset < 40; offset++)
     {
-      fprintf(stdout, "\nGot:\n");
-      print_hex(digest->length, buffer);
-      fprintf(stdout, "\nExpected:\n");
-      print_hex(digest->length, digest->data);
-      abort();
+      hash->update(ctx, offset, msg->data);
+      hash->update(ctx, 0, NULL);
+      hash->update(ctx, msg->length - offset, msg->data + offset);
+
+      hash->digest(ctx, digest->length, buffer);
+
+      if (MEMEQ(digest->length, digest->data, buffer) == 0)
+	{
+	  fprintf(stdout, "Offset %u\nGot:\n", offset);
+	  print_hex(digest->length, buffer);
+	  fprintf(stdout, "\nExpected:\n");
+	  print_hex(digest->length, digest->data);
+	  abort();
+	}
     }
 
   memset(buffer, 0, digest->length);