From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-bn3nam01on0105.outbound.protection.outlook.com ([104.47.33.105]:23296 "EHLO NAM01-BN3-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1032105AbeCAP0V (ORCPT ); Thu, 1 Mar 2018 10:26:21 -0500 From: Sasha Levin To: "stable@vger.kernel.org" , "stable-commits@vger.kernel.org" CC: Jing Xia , Chunyan Zhang , Steven Rostedt , Sasha Levin Subject: [added to the 4.1 stable tree] tracing: Fix crash when it fails to alloc ring buffer Date: Thu, 1 Mar 2018 15:23:11 +0000 Message-ID: <20180301152116.1486-72-alexander.levin@microsoft.com> References: <20180301152116.1486-1-alexander.levin@microsoft.com> In-Reply-To: <20180301152116.1486-1-alexander.levin@microsoft.com> Content-Language: en-US Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org List-ID: From: Jing Xia This patch has been added to the 4.1 stable tree. If you have any objections, please let us know. =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D [ Upstream commit 24f2aaf952ee0b59f31c3a18b8b36c9e3d3c2cf5 ] Double free of the ring buffer happens when it fails to alloc new ring buffer instance for max_buffer if TRACER_MAX_TRACE is configured. The root cause is that the pointer is not set to NULL after the buffer is freed in allocate_trace_buffers(), and the freeing of the ring buffer is invoked again later if the pointer is not equal to Null, as: instance_mkdir() |-allocate_trace_buffers() |-allocate_trace_buffer(tr, &tr->trace_buffer...) |-allocate_trace_buffer(tr, &tr->max_buffer...) // allocate fail(-ENOMEM),first free // and the buffer pointer is not set to null |-ring_buffer_free(tr->trace_buffer.buffer) // out_free_tr |-free_trace_buffers() |-free_trace_buffer(&tr->trace_buffer); //if trace_buffer is not null, free again |-ring_buffer_free(buf->buffer) |-rb_free_cpu_buffer(buffer->buffers[cpu]) // ring_buffer_per_cpu is null, and // crash in ring_buffer_per_cpu->pages Link: http://lkml.kernel.org/r/20171226071253.8968-1-chunyan.zhang@spreadtr= um.com Cc: stable@vger.kernel.org Fixes: 737223fbca3b1 ("tracing: Consolidate buffer allocation code") Signed-off-by: Jing Xia Signed-off-by: Chunyan Zhang Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Sasha Levin --- kernel/trace/trace.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 8437927928bc..d03f7eadc1f3 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -6464,7 +6464,9 @@ static int allocate_trace_buffers(struct trace_array = *tr, int size) allocate_snapshot ? size : 1); if (WARN_ON(ret)) { ring_buffer_free(tr->trace_buffer.buffer); + tr->trace_buffer.buffer =3D NULL; free_percpu(tr->trace_buffer.data); + tr->trace_buffer.data =3D NULL; return -ENOMEM; } tr->allocated_snapshot =3D allocate_snapshot; --=20 2.14.1