[PATCH][GIT PULL][v2.6.36] tracing: t_start: reset FTRACE_ITER_HASH in case of seek/pread

[Steven Rostedt <rostedt@goodmis.org>]

Ingo,

The previous fixed only fixed lseek, Chris's fix also handles pread().

Please pull the latest tip/perf/urgent tree, which can be found at:

  git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace.git
tip/perf/urgent


Chris Wright (1):
      tracing: t_start: reset FTRACE_ITER_HASH in case of seek/pread

----
 kernel/trace/ftrace.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---------------------------
commit df09162550fbb53354f0c88e85b5d0e6129ee9cc
Author: Chris Wright <chrisw@sous-sol.org>
Date:   Thu Sep 9 16:34:59 2010 -0700

    tracing: t_start: reset FTRACE_ITER_HASH in case of seek/pread
    
    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>

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 83a16e9..fa7ece6 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -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;
 	}