Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932967AbcDKNcq (ORCPT ); Mon, 11 Apr 2016 09:32:46 -0400 Received: from mx2.suse.de ([195.135.220.15]:37494 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932569AbcDKNYT (ORCPT ); Mon, 11 Apr 2016 09:24:19 -0400 X-Amavis-Alert: BAD HEADER SECTION, Duplicate header field: "References" From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, "Steven Rostedt (Red Hat)" , Jiri Slaby Subject: [PATCH 3.12 86/98] tracing: Fix crash from reading trace_pipe with sendfile Date: Mon, 11 Apr 2016 15:23:28 +0200 Message-Id: X-Mailer: git-send-email 2.8.1 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1229 Lines: 42 From: "Steven Rostedt (Red Hat)" 3.12-stable review patch. If anyone has any objections, please let me know. =============== 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: Jiri Slaby --- 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 1b51436db225..12cff54899ee 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4362,7 +4362,10 @@ 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; -- 2.8.1