From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9338CC388F7 for ; Tue, 3 Nov 2020 20:49:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 454F42242A for ; Tue, 3 Nov 2020 20:49:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604436545; bh=UUZhJu7PlHJEOTeScATk6/XWUhsNVq7I6xnmh+OhpVc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=IPfE8rg1z/LEAlzjOb9ar+mAeXzN3o5mkhylgpM4KVrE3F4Nx7Iz4jYSN8Mev06AX yZ8QbVWCYn8XOo86BfFpf4D/s4imoQkH/zM0wcq0y2KdI7FENFdN9Z2eHuWtnIpXUR EoPAvO6sopndb8s6iokDADJ92m/ipX2yxv2FFspw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731694AbgKCUtE (ORCPT ); Tue, 3 Nov 2020 15:49:04 -0500 Received: from mail.kernel.org ([198.145.29.99]:39022 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731401AbgKCUsA (ORCPT ); Tue, 3 Nov 2020 15:48:00 -0500 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9A38220719; Tue, 3 Nov 2020 20:47:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604436480; bh=UUZhJu7PlHJEOTeScATk6/XWUhsNVq7I6xnmh+OhpVc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Ar2zxCfrAW/3pMDIcjvchfrXr/XuFfsbbt2xWrrPFU5r5i7UDXuUEH5BySP0ehWAx Ex0c2Ox7MLJT4izf5OlRrhYUjU8OI3d9bsx9lvHV48j5ztuO6eDeRV+A1svyOmTy7X 059NW8PLZ2f/4GlUteqCnaAENPExwqq42B1Prwlo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Gaurav Kohli , "Steven Rostedt (VMware)" Subject: [PATCH 5.9 261/391] tracing: Fix race in trace_open and buffer resize call Date: Tue, 3 Nov 2020 21:35:12 +0100 Message-Id: <20201103203404.635910328@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201103203348.153465465@linuxfoundation.org> References: <20201103203348.153465465@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Gaurav Kohli commit bbeb97464eefc65f506084fd9f18f21653e01137 upstream. Below race can come, if trace_open and resize of cpu buffer is running parallely on different cpus CPUX CPUY ring_buffer_resize atomic_read(&buffer->resize_disabled) tracing_open tracing_reset_online_cpus ring_buffer_reset_cpu rb_reset_cpu rb_update_pages remove/insert pages resetting pointer This race can cause data abort or some times infinte loop in rb_remove_pages and rb_insert_pages while checking pages for sanity. Take buffer lock to fix this. Link: https://lkml.kernel.org/r/1601976833-24377-1-git-send-email-gkohli@codeaurora.org Cc: stable@vger.kernel.org Fixes: b23d7a5f4a07a ("ring-buffer: speed up buffer resets by avoiding synchronize_rcu for each CPU") Signed-off-by: Gaurav Kohli Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Greg Kroah-Hartman --- kernel/trace/ring_buffer.c | 10 ++++++++++ 1 file changed, 10 insertions(+) --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -4866,6 +4866,9 @@ void ring_buffer_reset_cpu(struct trace_ if (!cpumask_test_cpu(cpu, buffer->cpumask)) return; + /* prevent another thread from changing buffer sizes */ + mutex_lock(&buffer->mutex); + atomic_inc(&cpu_buffer->resize_disabled); atomic_inc(&cpu_buffer->record_disabled); @@ -4876,6 +4879,8 @@ void ring_buffer_reset_cpu(struct trace_ atomic_dec(&cpu_buffer->record_disabled); atomic_dec(&cpu_buffer->resize_disabled); + + mutex_unlock(&buffer->mutex); } EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu); @@ -4889,6 +4894,9 @@ void ring_buffer_reset_online_cpus(struc struct ring_buffer_per_cpu *cpu_buffer; int cpu; + /* prevent another thread from changing buffer sizes */ + mutex_lock(&buffer->mutex); + for_each_online_buffer_cpu(buffer, cpu) { cpu_buffer = buffer->buffers[cpu]; @@ -4907,6 +4915,8 @@ void ring_buffer_reset_online_cpus(struc atomic_dec(&cpu_buffer->record_disabled); atomic_dec(&cpu_buffer->resize_disabled); } + + mutex_unlock(&buffer->mutex); } /**