From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752915AbcFEKn3 (ORCPT ); Sun, 5 Jun 2016 06:43:29 -0400 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:21915 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752563AbcFEKWr (ORCPT ); Sun, 5 Jun 2016 06:22:47 -0400 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: "Steven Rostedt (Red Hat)" , stable@vger.kernel.org#2.6.30+, Willy Tarreau Subject: [PATCH 3.10 045/143] tracing: Fix crash from reading trace_pipe with sendfile Date: Sun, 5 Jun 2016 12:19:08 +0200 Message-Id: <1465122046-9645-46-git-send-email-w@1wt.eu> X-Mailer: git-send-email 2.8.0.rc2.1.gbe9624a In-Reply-To: <1465122046-9645-1-git-send-email-w@1wt.eu> References: <1465122046-9645-1-git-send-email-w@1wt.eu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Steven Rostedt (Red Hat)" commit a29054d9478d0435ab01b7544da4f674ab13f533 upstream. If tracing contains data and the trace_pipe file is read with sendfile(), then it can trigger a NULL pointer dereference and various BUG_ON within the VM code. There's a patch to fix this in the splice_to_pipe() code, but it's also a good idea to not let that happen from trace_pipe either. Link: http://lkml.kernel.org/r/1457641146-9068-1-git-send-email-rabin@rab.in Cc: stable@vger.kernel.org # 2.6.30+ Reported-by: Rabin Vincent Signed-off-by: Steven Rostedt Signed-off-by: Willy Tarreau --- kernel/trace/trace.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 640e4c4..eff26a9 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4351,7 +4351,10 @@ static ssize_t tracing_splice_read_pipe(struct file *filp, spd.nr_pages = i; - ret = splice_to_pipe(pipe, &spd); + if (i) + ret = splice_to_pipe(pipe, &spd); + else + ret = 0; out: splice_shrink_spd(&spd); return ret; -- 2.8.0.rc2.1.gbe9624a