[34-longterm 064/260] tracing: t_start: reset FTRACE_ITER_HASH in case of seek/pread

Paul Gortmaker
2011-01-02T07:22:44Z

From: Chris Wright <chrisw@sous-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@google.com>
Cc: Eugene Teo <eugene@redhat.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
kernel/trace/ftrace.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 7d51cab..73dedb3 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1488,6 +1488,8 @@ 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;
}

--
1.7.3.3