From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from wtarreau.pck.nerim.net ([62.212.114.60]:9410 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755711AbbILXOP (ORCPT ); Sat, 12 Sep 2015 19:14:15 -0400 Message-Id: <20150912225608.764079700@1wt.eu> Date: Sun, 13 Sep 2015 00:56:57 +0200 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Vince Weaver , Sasha Levin , Steven Rostedt , Ben Hutchings , Willy Tarreau Subject: [PATCH 2.6.32 51/62] tracing/filter: Do not WARN on operand count going below zero MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 In-Reply-To: <08d3b586eb2e764308c3de9ee398a17c@local> Sender: stable-owner@vger.kernel.org List-ID: 2.6.32-longterm review patch. If anyone has any objections, please let me know. ------------------ From: "Steven Rostedt (Red Hat)" 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: Ben Hutchings (cherry picked from commit b43dd35952747f563d0dec7aefb7570260f10353) Signed-off-by: Willy Tarreau --- 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 098a1dc..ab10a9f 100644 --- a/kernel/trace/trace_events_filter.c +++ b/kernel/trace/trace_events_filter.c @@ -1085,7 +1085,9 @@ 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) { -- 1.7.12.2.21.g234cd45.dirty