Apply by doing:
        cd /usr/src
        patch -p0 < 014_rnd.patch

And then rebuild your kernel.

Index: sys/dev/rnd.c
===================================================================
RCS file: /cvs/src/sys/dev/rnd.c,v
retrieving revision 1.67
retrieving revision 1.67.2.1
diff -u -p -r1.67 -r1.67.2.1
--- sys/dev/rnd.c	15 Mar 2004 14:17:25 -0000	1.67
+++ sys/dev/rnd.c	17 Jul 2004 02:57:54 -0000	1.67.2.1
@@ -264,6 +264,7 @@ int	rnd_debug = 0x0000;
  * For a pool of size 64, try x^64+x^62+x^38+x^10+x^6+x+1.
  */
 #define POOLBITS (POOLWORDS*32)
+#define POOLBYTES (POOLWORDS*4)
 #if POOLWORDS == 2048
 #define	TAP1	1638
 #define	TAP2	1231
@@ -964,15 +965,17 @@ randomread(dev, uio, ioflag)
 	struct uio *uio;
 	int	ioflag;
 {
-	int	ret = 0;
-	int	i;
+	int		ret = 0;
+	int		i;
+	u_int32_t 	*buf;
 
 	if (uio->uio_resid == 0)
 		return 0;
 
+	MALLOC(buf, u_int32_t *, POOLBYTES, M_TEMP, M_WAITOK);
+
 	while (!ret && uio->uio_resid > 0) {
-		u_int32_t buf[ POOLWORDS ];
-		int	n = min(sizeof(buf), uio->uio_resid);
+		int	n = min(POOLBYTES, uio->uio_resid);
 
 		switch(minor(dev)) {
 		case RND_RND:
@@ -1033,6 +1036,8 @@ randomread(dev, uio, ioflag)
 		if (n != 0 && ret == 0)
 			ret = uiomove((caddr_t)buf, n, uio);
 	}
+
+	FREE(buf, M_TEMP);
 	return ret;
 }
 
@@ -1126,7 +1131,8 @@ randomwrite(dev, uio, flags)
 	struct uio *uio;
 	int	flags;
 {
-	int	ret = 0;
+	int		ret = 0;
+	u_int32_t	*buf;
 
 	if (minor(dev) == RND_RND || minor(dev) == RND_PRND)
 		return ENXIO;
@@ -1134,9 +1140,10 @@ randomwrite(dev, uio, flags)
 	if (uio->uio_resid == 0)
 		return 0;
 
+	MALLOC(buf, u_int32_t *, POOLBYTES, M_TEMP, M_WAITOK);
+
 	while (!ret && uio->uio_resid > 0) {
-		u_int32_t	buf[ POOLWORDS ];
-		u_short		n = min(sizeof(buf),uio->uio_resid);
+		u_short	n = min(POOLBYTES, uio->uio_resid);
 
 		ret = uiomove((caddr_t)buf, n, uio);
 		if (!ret) {
@@ -1149,6 +1156,7 @@ randomwrite(dev, uio, flags)
 	if (minor(dev) == RND_ARND && !ret)
 		arc4random_initialized = 0;
 
+	FREE(buf, M_TEMP);
 	return ret;
 }