Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932756AbcDBA4i (ORCPT ); Fri, 1 Apr 2016 20:56:38 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:54362 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932732AbcDBA4f (ORCPT ); Fri, 1 Apr 2016 20:56:35 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Steven Rostedt , Kamal Mostafa Subject: [PATCH 3.19.y-ckt 107/170] tracing: Fix crash from reading trace_pipe with sendfile Date: Fri, 1 Apr 2016 17:53:13 -0700 Message-Id: <1459558456-24452-108-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1459558456-24452-1-git-send-email-kamal@canonical.com> References: <1459558456-24452-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.19 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1286 Lines: 42 3.19.8-ckt18 -stable review patch. If anyone has any objections, please let me know. ---8<------------------------------------------------------------ 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: Kamal Mostafa --- 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 361a827..bd3e6b1 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4705,7 +4705,10 @@ 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; -- 2.7.4