--- /n/sources/plan9/sys/src/cmd/exportfs/exportsrv.c	Tue Sep 22 06:04:31 2026
+++ /sys/src/cmd/exportfs/exportsrv.c	Tue Sep 22 00:00:00 2026
@@ -25,6 +25,7 @@
 char Enomem[] = "No memory";
 char Eversion[] = "Bad 9P2000 version";
 char Ereadonly[] = "File system read only";
+char Ebadname[] = "Bad character in file name";
 
 ulong messagesize;
 int readonly;
@@ -159,6 +160,12 @@
 	return n;
 }
 
+static int
+badname(char *name)
+{
+	return *name == '\0' || strchr(name, '/') != nil;
+}
+
 void
 Xwalk(Fsrpc *t)
 {
@@ -189,6 +196,11 @@
 			break;
 		}
 
+		if(badname(t->work.wname[i])) {
+			e = Ebadname;
+			break;
+		}
+
 		if(strcmp(t->work.wname[i], "..") == 0) {
 			if(f->f->parent == nil) {
 				e = Exmnt;
@@ -316,6 +328,12 @@
 	}
 	
 
+	if(badname(t->work.name)) {
+		reply(&t->work, &rhdr, Ebadname);
+		t->busy = 0;
+		return;
+	}
+
 	path = makepath(f->f, t->work.name);
 	f->fid = create(path, t->work.mode, t->work.perm);
 	free(path);