Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758862AbcDJS5y (ORCPT ); Sun, 10 Apr 2016 14:57:54 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:52513 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757985AbcDJSsn (ORCPT ); Sun, 10 Apr 2016 14:48:43 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Rabin Vincent , Steven Rostedt Subject: [PATCH 4.5 181/238] tracing: Fix crash from reading trace_pipe with sendfile Date: Sun, 10 Apr 2016 11:35:58 -0700 Message-Id: <20160410183506.443440938@linuxfoundation.org> X-Mailer: git-send-email 2.8.0 In-Reply-To: <20160410183456.398741366@linuxfoundation.org> References: <20160410183456.398741366@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1129 Lines: 40 4.5-stable review patch. If anyone has any objections, please let me know. ------------------ 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 Reported-by: Rabin Vincent Signed-off-by: Steven Rostedt Signed-off-by: Greg Kroah-Hartman --- kernel/trace/trace.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4949,7 +4949,10 @@ static ssize_t tracing_splice_read_pipe( 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;