* thread.c (rb_fd_rcopy): added an argument guard.

  Patch by NAKAMURA Usaku. [Bug #5306] [ruby-core:39435]



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@33266 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 3 insertions, 1 deletions

diff --git a/thread.c b/thread.c
index 4f8a907764..10b73eb3e4 100644
--- a/thread.c
+++ b/thread.c
@@ -2469,7 +2469,9 @@ rb_fd_rcopy(fd_set *dst, rb_fdset_t *src)
 {
     int max = rb_fd_max(src);
 
-    if (max > FD_SETSIZE) {
+    /* we assume src is the result of select() with dst, so dst should be
+     * larger or equal than src. */
+    if (max > FD_SETSIZE || max > dst->fd_count) {
 	rb_raise(rb_eArgError, "too large fdsets");
     }