From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754042Ab3HBRRH (ORCPT ); Fri, 2 Aug 2013 13:17:07 -0400 Received: from mailhub.sw.ru ([195.214.232.25]:35345 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752478Ab3HBRRG (ORCPT ); Fri, 2 Aug 2013 13:17:06 -0400 From: Andrew Vagin To: linux-kernel@vger.kernel.org Cc: Andrew Vagin , Steven Rostedt , Frederic Weisbecker , Ingo Molnar , David Sharp , Hiraku Toyooka , Arjan van de Ven , Masami Hiramatsu Subject: [PATCH] tracing: a few fields of struct trace_iterator are zeroed by mistake Date: Fri, 2 Aug 2013 21:16:43 +0400 Message-Id: <1375463803-3085183-1-git-send-email-avagin@openvz.org> X-Mailer: git-send-email 1.7.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org tracing_read_pipe zeros all fields bellow "seq". The declaration contains a comment about that, but it doesn't help. The first field is "snapshot", it's true when current open file is snapshot. Looks obvious, that it should not be zeroed. The second field is "started". It was converted from cpumask_t to cpumask_var_t (v2.6.28-4983-g4462344) or by another words it was converted from cpumask to pointer on cpumask. Currently the reference on "started" memory is lost after the first read from tracing_read_pipe and a proper object will never be freed. The "started" is never dereferenced for trace_pipe, because trace_pipe can't have the TRACE_FILE_ANNOTATE options (why?). Cc: Steven Rostedt Cc: Frederic Weisbecker Cc: Ingo Molnar Cc: David Sharp Cc: Hiraku Toyooka Cc: Arjan van de Ven Cc: Masami Hiramatsu Signed-off-by: Andrew Vagin --- include/linux/ftrace_event.h | 10 ++++++---- kernel/trace/trace.c | 1 + 2 files changed, 7 insertions(+), 4 deletions(-) diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h index 4372658..44cdc11 100644 --- a/include/linux/ftrace_event.h +++ b/include/linux/ftrace_event.h @@ -78,6 +78,11 @@ struct trace_iterator { /* trace_seq for __print_flags() and __print_symbolic() etc. */ struct trace_seq tmp_seq; + cpumask_var_t started; + + /* it's true when current open file is snapshot */ + bool snapshot; + /* The below is zeroed out in pipe_read */ struct trace_seq seq; struct trace_entry *ent; @@ -90,10 +95,7 @@ struct trace_iterator { loff_t pos; long idx; - cpumask_var_t started; - - /* it's true when current open file is snapshot */ - bool snapshot; + /* All new field here will be zeroed out in pipe_read */ }; enum trace_iter_flags { diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 0cd500b..897f553 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4166,6 +4166,7 @@ waitagain: memset(&iter->seq, 0, sizeof(struct trace_iterator) - offsetof(struct trace_iterator, seq)); + cpumask_clear(iter->started); iter->pos = -1; trace_event_read_lock(); -- 1.7.1