$NetBSD: patch-ad,v 1.3 2004/05/13 11:42:43 taca Exp $

--- src/lhext.c.orig	2000-10-04 23:57:38.000000000 +0900
+++ src/lhext.c
@@ -190,8 +190,13 @@ extract_one(afp, hdr)
 		q = (char *) rindex(hdr->name, '/') + 1;
 	}
 	else {
+		if (is_directory_traversal(q)) {
+		  fprintf(stderr, "Possible directory traversal hack attempt in %s\n", q);
+		  exit(111);
+		}
+
 		if (*q == '/') {
-			q++;
+			while (*q == '/') { q++; }
 			/*
 			 * if OSK then strip device name
 			 */
@@ -419,6 +424,33 @@ cmd_extract()
 	return;
 }
 
+int
+is_directory_traversal(char *string)
+{
+  unsigned int type = 0; /* 0 = new, 1 = only dots, 2 = other chars than dots */
+  char *temp;
+
+  temp = string;
+
+  while (*temp != 0) {
+    if (temp[0] == '/') {
+      if (type == 1) { return 1; }
+      type = 0;
+      temp++;
+      continue;
+    }
+
+    if ((temp[0] == '.') && (type < 2))
+      type = 1;
+    if (temp[0] != '.')
+      type = 2;
+
+    temp++;
+  } /* while */
+
+  return (type == 1);
+}
+
 /* Local Variables: */
 /* mode:c */
 /* tab-width:4 */