diff -u util-linux-2.17.2/debian/changelog util-linux-2.17.2/debian/changelog
--- util-linux-2.17.2/debian/changelog
+++ util-linux-2.17.2/debian/changelog
@@ -1,3 +1,10 @@
+util-linux (2.17.2-0ubuntu1.10.10.2) maverick-proposed; urgency=low
+
+  * Fixes a segfault on umount, caused due to an empty mtab entry. 
+    (LP: #579858)
+
+ -- Surbhi Palande <surbhi.palande@canonical.com>  Wed, 26 Jan 2011 18:25:55 +0200
+
 util-linux (2.17.2-0ubuntu1.10.10.1) maverick-security; urgency=low
 
   * SECURITY UPDATE: arbitrary unmount with fuse (LP: #670622)
diff -u util-linux-2.17.2/mount/umount.c util-linux-2.17.2/mount/umount.c
--- util-linux-2.17.2/mount/umount.c
+++ util-linux-2.17.2/mount/umount.c
@@ -253,15 +253,20 @@
 		res = mount(spec, node, NULL,
 			    MS_MGC_VAL | MS_REMOUNT | MS_RDONLY, NULL);
 		if (res == 0) {
-			struct my_mntent remnt;
 			fprintf(stderr,
 				_("umount: %s busy - remounted read-only\n"),
 				spec);
-			remnt.mnt_type = remnt.mnt_fsname = NULL;
-			remnt.mnt_dir = xstrdup(node);
-			remnt.mnt_opts = xstrdup("ro");
-			if (!nomtab)
+			if (mc && !nomtab) {
+				/* update mtab if the entry is there */
+				struct my_mntent remnt;
+				remnt.mnt_fsname = mc->m.mnt_fsname;
+				remnt.mnt_dir = mc->m.mnt_dir;
+				remnt.mnt_type = mc->m.mnt_type;
+				remnt.mnt_opts = "ro";
+				remnt.mnt_freq = 0;
+				remnt.mnt_passno = 0;
 				update_mtab(node, &remnt);
+			}
 			return 0;
 		} else if (errno != EBUSY) { 	/* hmm ... */
 			perror("remount");