tracing: t_start: reset FTRACE_ITER_HASH in case of seek/pread
authorChris Wright <chrisw@sous-sol.org>
Thu, 9 Sep 2010 23:34:59 +0000 (16:34 -0700)
committerSteven Rostedt <rostedt@goodmis.org>
Fri, 10 Sep 2010 02:43:49 +0000 (22:43 -0400)
Be sure to avoid entering t_show() with FTRACE_ITER_HASH set without
having properly started the iterator to iterate the hash.  This case is
degenerate and, as discovered by Robert Swiecki, can cause t_hash_show()
to misuse a pointer.  This causes a NULL ptr deref with possible security
implications.  Tracked as CVE-2010-3079.

Cc: Robert Swiecki <swiecki@google.com>
Cc: Eugene Teo <eugene@redhat.com>
Cc: <stable@kernel.org>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
kernel/trace/ftrace.c

index 83a16e9ee518e4bd3b03b059f7ac372547a0e23b..fa7ece649fe1bcad7b0db621fa8579e91860fb04 100644 (file)
@@ -1510,6 +1510,8 @@ static void *t_start(struct seq_file *m, loff_t *pos)
                if (*pos > 0)
                        return t_hash_start(m, pos);
                iter->flags |= FTRACE_ITER_PRINTALL;
+               /* reset in case of seek/pread */
+               iter->flags &= ~FTRACE_ITER_HASH;
                return iter;
        }