From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753299AbbJTA5U (ORCPT ); Mon, 19 Oct 2015 20:57:20 -0400 Received: from mail.kernel.org ([198.145.29.136]:55001 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753168AbbJTAvQ (ORCPT ); Mon, 19 Oct 2015 20:51:16 -0400 From: lizf@kernel.org To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, "Steven Rostedt (Red Hat)" , Zefan Li Subject: [PATCH 3.4 46/65] tracing/filter: Do not WARN on operand count going below zero Date: Tue, 20 Oct 2015 08:47:56 +0800 Message-Id: <1445302095-4695-46-git-send-email-lizf@kernel.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1445302030-4607-1-git-send-email-lizf@kernel.org> References: <1445302030-4607-1-git-send-email-lizf@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Steven Rostedt (Red Hat)" 3.4.110-rc1 review patch. If anyone has any objections, please let me know. ------------------ commit b4875bbe7e68f139bd3383828ae8e994a0df6d28 upstream. When testing the fix for the trace filter, I could not come up with a scenario where the operand count goes below zero, so I added a WARN_ON_ONCE(cnt < 0) to the logic. But there is legitimate case that it can happen (although the filter would be wrong). # echo '>' > /sys/kernel/debug/events/ext4/ext4_truncate_exit/filter That is, a single operation without any operands will hit the path where the WARN_ON_ONCE() can trigger. Although this is harmless, and the filter is reported as a error. But instead of spitting out a warning to the kernel dmesg, just fail nicely and report it via the proper channels. Link: http://lkml.kernel.org/r/558C6082.90608@oracle.com Reported-by: Vince Weaver Reported-by: Sasha Levin Signed-off-by: Steven Rostedt Signed-off-by: Zefan Li --- kernel/trace/trace_events_filter.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c index 3b04aec..ae6c572 100644 --- a/kernel/trace/trace_events_filter.c +++ b/kernel/trace/trace_events_filter.c @@ -1372,7 +1372,9 @@ static int check_preds(struct filter_parse_state *ps) } cnt--; n_normal_preds++; - WARN_ON_ONCE(cnt < 0); + /* all ops should have operands */ + if (cnt < 0) + break; } if (cnt != 1 || !n_normal_preds || n_logical_preds >= n_normal_preds) { -- 1.9.1