--- a/ChangeLog	Thu Jun 21 11:25:53 2018 -0700
+++ b/ChangeLog	Thu Jun 21 12:28:34 2018 -0700
@@ -1,5 +1,18 @@
 2018-06-21  Paul Eggert  <eggert@cs.ucla.edu>
 
+	random_r: do not crash if state is unaligned
+	Problem reported by Bruce Korb in:
+	https://lists.gnu.org/r/bug-gnulib/2018-06/msg00030.html
+	I reproduced the crash on 32-bit sparc with Oracle Studio 12.6
+	with 'cc -O2 -xmemalign=8s'.
+	* lib/random_r.c: Include string.h, for memcpy.
+	(get_int32, set_int32): New functions.
+	(__srandom_r, __initstate_r, __setstate_r, __random_r):
+	Use them to avoid assumption that state pointer is aligned.
+	(__random_r): Avoid integer overflow if INT_MAX == UINT32_MAX.
+	* tests/test-random_r.c (test_failed): New function.
+	(main): Use it, to test for alignment bugs.
+
 	random_r: omit unnecessary include
 	* lib/random_r.c: Do not include limits.h.
 

--- a/lib/random_r.c	Thu Jun 21 11:25:53 2018 -0700
+++ b/lib/random_r.c	Thu Jun 21 12:28:34 2018 -0700
@@ -69,6 +69,7 @@
 
 #include <errno.h>
 #include <stddef.h>
+#include <string.h>
 
 
 /* An improved random number generation package.  In addition to the standard
@@ -160,7 +161,19 @@
   { DEG_0, DEG_1, DEG_2, DEG_3, DEG_4 }
 };
 
+static int32_t
+get_int32 (void *p)
+{
+  int32_t v;
+  memcpy (&v, p, sizeof v);
+  return v;
+}
 
+static void
+set_int32 (void *p, int32_t v)
+{
+  memcpy (p, &v, sizeof v);
+}
 
 
 /* Initialize the random number generator based on the given seed.  If the
@@ -191,7 +204,7 @@
   /* We must make sure the seed is not 0.  Take arbitrarily 1 in this case.  */
   if (seed == 0)
     seed = 1;
-  state[0] = seed;
+  set_int32 (&state[0], seed);
   if (type == TYPE_0)
     goto done;
 
@@ -208,7 +221,7 @@
       word = 16807 * lo - 2836 * hi;
       if (word < 0)
         word += 2147483647;
-      *++dst = word;
+      set_int32 (++dst, word);
     }
 
   buf->fptr = &state[buf->rand_sep];
@@ -251,10 +264,10 @@
   if (old_state != NULL)
     {
       int old_type = buf->rand_type;
-      if (old_type == TYPE_0)
-        old_state[-1] = TYPE_0;
-      else
-        old_state[-1] = (MAX_TYPES * (buf->rptr - old_state)) + old_type;
+      set_int32 (&old_state[-1],
+                 (old_type == TYPE_0
+                  ? TYPE_0
+                  : (MAX_TYPES * (buf->rptr - old_state)) + old_type));
     }
 
   int type;
@@ -284,9 +297,8 @@
 
   __srandom_r (seed, buf);
 
-  state[-1] = TYPE_0;
-  if (type != TYPE_0)
-    state[-1] = (buf->rptr - state) * MAX_TYPES + type;
+  set_int32 (&state[-1],
+             type == TYPE_0 ? TYPE_0 : (buf->rptr - state) * MAX_TYPES + type);
 
   return 0;
 
@@ -320,12 +332,12 @@
 
   old_type = buf->rand_type;
   old_state = buf->state;
-  if (old_type == TYPE_0)
-    old_state[-1] = TYPE_0;
-  else
-    old_state[-1] = (MAX_TYPES * (buf->rptr - old_state)) + old_type;
+  set_int32 (&old_state[-1],
+             (old_type == TYPE_0
+              ? TYPE_0
+              : (MAX_TYPES * (buf->rptr - old_state)) + old_type));
 
-  type = new_state[-1] % MAX_TYPES;
+  type = get_int32 (&new_state[-1]) % MAX_TYPES;
   if (type < TYPE_0 || type > TYPE_4)
     goto fail;
 
@@ -335,7 +347,7 @@
 
   if (type != TYPE_0)
     {
-      int rear = new_state[-1] / MAX_TYPES;
+      int rear = get_int32 (&new_state[-1]) / MAX_TYPES;
       buf->rptr = &new_state[rear];
       buf->fptr = &new_state[(rear + separation) % degree];
     }
@@ -375,8 +387,9 @@
 
   if (buf->rand_type == TYPE_0)
     {
-      int32_t val = ((state[0] * 1103515245U) + 12345U) & 0x7fffffff;
-      state[0] = val;
+      int32_t val = (((get_int32 (&state[0]) * 1103515245U) + 12345U)
+                     & 0x7fffffff);
+      set_int32 (&state[0], val);
       *result = val;
     }
   else
@@ -384,9 +397,12 @@
       int32_t *fptr = buf->fptr;
       int32_t *rptr = buf->rptr;
       int32_t *end_ptr = buf->end_ptr;
-      uint32_t val;
-
-      val = *fptr += (uint32_t) *rptr;
+      /* F and R are unsigned int, not uint32_t, to avoid undefined
+         overflow behavior on platforms where INT_MAX == UINT32_MAX.  */
+      unsigned int f = get_int32 (fptr);
+      unsigned int r = get_int32 (rptr);
+      uint32_t val = f + r;
+      set_int32 (fptr, val);
       /* Chucking least random bit.  */
       *result = val >> 1;
       ++fptr;

--- a/tests/test-random_r.c	Thu Jun 21 11:25:53 2018 -0700
+++ b/tests/test-random_r.c	Thu Jun 21 12:28:34 2018 -0700
@@ -29,16 +29,17 @@
 
 #include "macros.h"
 
-int
-main ()
+static int
+test_failed (int alignment)
 {
   struct random_data rand_state;
-  char buf[128];
+  char buf[128 + sizeof (int32_t)];
   unsigned int i;
   unsigned int n_big = 0;
 
   rand_state.state = NULL;
-  if (initstate_r (time (NULL), buf, sizeof buf, &rand_state))
+  if (initstate_r (time (NULL), buf + alignment, sizeof buf - alignment,
+                   &rand_state))
     return 1;
   for (i = 0; i < 1000; i++)
     {
@@ -52,3 +53,13 @@
   /* Fail if none of the numbers were larger than RAND_MAX / 2.  */
   return !n_big;
 }
+
+int
+main ()
+{
+  int alignment;
+  for (alignment = 0; alignment < sizeof (int32_t); alignment++)
+    if (test_failed (alignment))
+      return 1;
+  return 0;
+}