linux-kernel - [076/129] tracing: t_start: reset FTRACE_ITER

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Message-Id: <20100918191303.863791076@clark.site>
Date:	Sat, 18 Sep 2010 12:12:54 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Robert Swiecki <swiecki@...gle.com>,
	Eugene Teo <eugene@...hat.com>,
	Chris Wright <chrisw@...s-sol.org>,
	Steven Rostedt <rostedt@...dmis.org>
Subject: [076/129] tracing: t_start: reset FTRACE_ITER_HASH in case of seek/pread

2.6.35-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Chris Wright <chrisw@...s-sol.org>

commit df09162550fbb53354f0c88e85b5d0e6129ee9cc upstream.

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@...gle.com>
Cc: Eugene Teo <eugene@...hat.com>
Signed-off-by: Chris Wright <chrisw@...s-sol.org>
Signed-off-by: Steven Rostedt <rostedt@...dmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 kernel/trace/ftrace.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1510,6 +1510,8 @@ static void *t_start(struct seq_file *m,
 		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;
 	}
 


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