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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 19C06C433FE for ; Tue, 8 Nov 2022 14:13:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235291AbiKHONq (ORCPT ); Tue, 8 Nov 2022 09:13:46 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52138 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235272AbiKHONl (ORCPT ); Tue, 8 Nov 2022 09:13:41 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3245F57B43 for ; Tue, 8 Nov 2022 06:13:40 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id C5ED46159E for ; Tue, 8 Nov 2022 14:13:39 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D8360C433C1; Tue, 8 Nov 2022 14:13:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1667916819; bh=E1LmpNVliSGZIkNGktuij19/8LIdGPIeZZGSAg8TBVk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=OlF3CnErZvKTXbcF02gmgpiSpqB1LT7so6jb37eTGnKjq6/L1xBKHRd/CheE4AOdT jEZCOTIsYdf+UF2TnKeN0M5jXPCbYqM1vbZ1fnvZOGSvaEXgDfgv62m4XzwOT8MCyi C93QB1SBBTXOzI/FzCBov5SECWKho53LnIYKWnQs= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Steven Noonan , Takashi Iwai , Roland Ruckerbauer , "Masami Hiramatsu (Google)" , "Steven Rostedt (Google)" Subject: [PATCH 6.0 143/197] ring-buffer: Check for NULL cpu_buffer in ring_buffer_wake_waiters() Date: Tue, 8 Nov 2022 14:39:41 +0100 Message-Id: <20221108133401.443870354@linuxfoundation.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221108133354.787209461@linuxfoundation.org> References: <20221108133354.787209461@linuxfoundation.org> User-Agent: quilt/0.67 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: Steven Rostedt (Google) commit 7433632c9ff68a991bd0bc38cabf354e9d2de410 upstream. On some machines the number of listed CPUs may be bigger than the actual CPUs that exist. The tracing subsystem allocates a per_cpu directory with access to the per CPU ring buffer via a cpuX file. But to save space, the ring buffer will only allocate buffers for online CPUs, even though the CPU array will be as big as the nr_cpu_ids. With the addition of waking waiters on the ring buffer when closing the file, the ring_buffer_wake_waiters() now needs to make sure that the buffer is allocated (with the irq_work allocated with it) before trying to wake waiters, as it will cause a NULL pointer dereference. While debugging this, I added a NULL check for the buffer itself (which is OK to do), and also NULL pointer checks against buffer->buffers (which is not fine, and will WARN) as well as making sure the CPU number passed in is within the nr_cpu_ids (which is also not fine if it isn't). Link: https://lore.kernel.org/all/87h6zklb6n.wl-tiwai@suse.de/ Link: https://lore.kernel.org/all/CAM6Wdxc0KRJMXVAA0Y=u6Jh2V=uWB-_Fn6M4xRuNppfXzL1mUg@mail.gmail.com/ Link: https://lkml.kernel.org/linux-trace-kernel/20221101191009.1e7378c8@rorschach.local.home Cc: stable@vger.kernel.org Cc: Steven Noonan Bugzilla: https://bugzilla.opensuse.org/show_bug.cgi?id=1204705 Reported-by: Takashi Iwai Reported-by: Roland Ruckerbauer Fixes: f3ddb74ad079 ("tracing: Wake up ring buffer waiters on closing of the file") Reviewed-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt (Google) Signed-off-by: Greg Kroah-Hartman --- kernel/trace/ring_buffer.c | 11 +++++++++++ 1 file changed, 11 insertions(+) --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -937,6 +937,9 @@ void ring_buffer_wake_waiters(struct tra struct ring_buffer_per_cpu *cpu_buffer; struct rb_irq_work *rbwork; + if (!buffer) + return; + if (cpu == RING_BUFFER_ALL_CPUS) { /* Wake up individual ones too. One level recursion */ @@ -945,7 +948,15 @@ void ring_buffer_wake_waiters(struct tra rbwork = &buffer->irq_work; } else { + if (WARN_ON_ONCE(!buffer->buffers)) + return; + if (WARN_ON_ONCE(cpu >= nr_cpu_ids)) + return; + cpu_buffer = buffer->buffers[cpu]; + /* The CPU buffer may not have been initialized yet */ + if (!cpu_buffer) + return; rbwork = &cpu_buffer->irq_work; }