[PATCH] ia64: Missing overflow check in mmap

Calling mmap with len == -1 was silently accepted.  The test in the generic
code was fixed in July 2003, but the fix didn't make it into the ia64-
specific code.

arch/ia64/kernel/sys_ia64.c

@@ -201,10 +201,16 @@ do_mmap2 (unsigned long addr, unsigned long len, int prot, int flags, int fd, un
 	 * A zero mmap always succeeds in Linux, independent of whether or not the
 	 * remaining arguments are valid.
 	 */
-	len = PAGE_ALIGN(len);
 	if (len == 0)
 		goto out;
 
+	/* Careful about overflows.. */
+	len = PAGE_ALIGN(len);
+	if (!len || len > TASK_SIZE) {
+		addr = -EINVAL;
+		goto out;
+	}
+
 	/*
 	 * Don't permit mappings into unmapped space, the virtual page table of a region,
 	 * or across a region boundary.  Note: RGN_MAP_LIMIT is equal to 2^n-PAGE_SIZE