Index: vm/vm_mmap.c
===================================================================
RCS file: /home/ncvs/src/sys/vm/vm_mmap.c,v
retrieving revision 1.186
diff -u -r1.186 vm_mmap.c
--- vm/vm_mmap.c	18 Mar 2004 20:58:51 -0000	1.186
+++ vm/vm_mmap.c	4 Apr 2004 10:55:23 -0000
@@ -341,14 +341,14 @@
 		 * permission although we opened it without asking
 		 * for it, bail out.
 		 */
-		if ((flags & MAP_SHARED) != 0 || vp->v_type == VCHR) {
+		if ((flags & MAP_SHARED) != 0) {
 			if ((fp->f_flag & FWRITE) != 0) {
 				maxprot |= VM_PROT_WRITE;
 			} else if ((prot & PROT_WRITE) != 0) {
 				error = EACCES;
 				goto done;
 			}
-		} else {
+		} else if (vp->v_type != VCHR || (fp->f_flag & FWRITE) != 0) {
 			maxprot |= VM_PROT_WRITE;
 		}
 		handle = (void *)vp;
@@ -1113,6 +1113,11 @@
 		/*
 		 * cdevs does not provide private mappings of any kind.
 		 */
+		if ((*maxprotp & VM_PROT_WRITE) == 0 &&
+		    (prot & PROT_WRITE) != 0) {
+			error = EACCES;
+			goto done;
+		}
 		/*
 		 * However, for XIG X server to continue to work,
 		 * we should allow the superuser to do it anyway.