From 4f29a7323a664994f633a7bcd5a1afc2914156fa Mon Sep 17 00:00:00 2001
From: mdw <mdw>
Date: Sat, 19 Oct 2002 18:55:08 +0000
Subject: [PATCH] Fix overflows in shift primitives.

---
 mpx.c     | 23 +++++++++++++++++------
 tests/mp  |  5 ++++-
 tests/mpx |  6 +++++-
 3 files changed, 26 insertions(+), 8 deletions(-)

diff --git a/mpx.c b/mpx.c
index b88bd49..d7ea70a 100644
--- a/mpx.c
+++ b/mpx.c
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: mpx.c,v 1.13 2002/10/19 17:56:50 mdw Exp $
+ * $Id: mpx.c,v 1.14 2002/10/19 18:55:08 mdw Exp $
  *
  * Low-level multiprecision arithmetic
  *
@@ -30,6 +30,9 @@
 /*----- Revision history --------------------------------------------------* 
  *
  * $Log: mpx.c,v $
+ * Revision 1.14  2002/10/19 18:55:08  mdw
+ * Fix overflows in shift primitives.
+ *
  * Revision 1.13  2002/10/19 17:56:50  mdw
  * Fix bit operations.  Test them (a bit) better.
  *
@@ -470,8 +473,12 @@ void mpx_lsl(mpw *dv, mpw *dvl, const mpw *av, const mpw *avl, size_t n)
   /* --- Handle a shift by a multiple of the word size --- */
 
   if (nb == 0) {
-    MPX_COPY(dv + nw, dvl, av, avl);
-    memset(dv, 0, MPWS(nw));
+    if (nw >= dvl - dv)
+      MPX_ZERO(dv, dvl);
+    else {
+      MPX_COPY(dv + nw, dvl, av, avl);
+      memset(dv, 0, MPWS(nw));
+    }
   }
 
   /* --- And finally the difficult case --- *
@@ -562,8 +569,12 @@ void mpx_lsr(mpw *dv, mpw *dvl, const mpw *av, const mpw *avl, size_t n)
 
   /* --- Handle a shift by a multiple of the word size --- */
 
-  if (nb == 0)
-    MPX_COPY(dv, dvl, av + nw, avl);
+  if (nb == 0) {
+    if (nw >= avl - av)
+      MPX_ZERO(dv, dvl);
+    else
+      MPX_COPY(dv, dvl, av + nw, avl);
+  }
 
   /* --- And finally the difficult case --- */
 
@@ -572,7 +583,7 @@ void mpx_lsr(mpw *dv, mpw *dvl, const mpw *av, const mpw *avl, size_t n)
     size_t nr = MPW_BITS - nb;
 
     av += nw;
-    w = *av++;
+    w = av < avl ? *av++ : 0;
     while (av < avl) {
       mpw t;
       if (dv >= dvl)
diff --git a/tests/mp b/tests/mp
index c451acb..98399a2 100644
--- a/tests/mp
+++ b/tests/mp
@@ -1,6 +1,6 @@
 # Test vectors for MP functions
 #
-# $Id: mp,v 1.13 2002/10/19 17:56:50 mdw Exp $
+# $Id: mp,v 1.14 2002/10/19 18:55:08 mdw Exp $
 
 add {
   5 4 9; 5 -4 1; -5 4 -1; -5 -4 -9;
@@ -34,6 +34,9 @@ lsr2c {
   -1 5 -1;
   1 5 0;
   -6 2 -2;
+  7 2 1;
+ -7 2 -2;
+  -7 -2 0;
 }
 
 setbit {
diff --git a/tests/mpx b/tests/mpx
index e8aabac..1603838 100644
--- a/tests/mpx
+++ b/tests/mpx
@@ -1,6 +1,6 @@
 # Test vectors for low-level MP functions
 #
-# $Id: mpx,v 1.8 2002/10/06 22:52:50 mdw Exp $
+# $Id: mpx,v 1.9 2002/10/19 18:55:08 mdw Exp $
 
 # --- Load-store tests ---
 #
@@ -50,6 +50,8 @@ lsl {
   01 2 04;
   01 4 10;
 
+  7 -1 0;
+
   # --- Copy shifts ---
 
   01 0 01;
@@ -133,6 +135,8 @@ lsr {
 
   04 2 01;
   10 4 01;
+  7 -1 0;
+  7 32 0;
 
   # --- Copy shifts ---
 
-- 
2.11.0