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 183F2C74A44 for ; Fri, 10 Mar 2023 15:24:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231816AbjCJPYm (ORCPT ); Fri, 10 Mar 2023 10:24:42 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56128 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233546AbjCJPYK (ORCPT ); Fri, 10 Mar 2023 10:24:10 -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 A7709E1B3 for ; Fri, 10 Mar 2023 07:14:03 -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 49E0E61976 for ; Fri, 10 Mar 2023 15:14:03 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1944EC433EF; Fri, 10 Mar 2023 15:14:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1678461242; bh=BHdafvUe2TqjGjZt7SIyXQ6hH3grLvOjN4qy0gd71RE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hgQsRWtdRiEN3crZeNBzL3d/Ah0fUOlQg1Ocg3MI93P4vFF1+n9JacTdYwlUesBlg ziIFxN8r9CCvmOzGT5aNMYqXyjZdyjLzNbv4ACbnELd6CFvm9RfNm+hTxp8Aupg8RB svsoNwvh1+57+V4oUW0psGJmJJVrKCwt1KFR2ADc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, TOTE Robot , Jia-Ju Bai , "Steven Rostedt (Google)" , Sasha Levin Subject: [PATCH 5.15 073/136] tracing: Add NULL checks for buffer in ring_buffer_free_read_page() Date: Fri, 10 Mar 2023 14:43:15 +0100 Message-Id: <20230310133709.360879807@linuxfoundation.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230310133706.811226272@linuxfoundation.org> References: <20230310133706.811226272@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: Jia-Ju Bai [ Upstream commit 3e4272b9954094907f16861199728f14002fcaf6 ] In a previous commit 7433632c9ff6, buffer, buffer->buffers and buffer->buffers[cpu] in ring_buffer_wake_waiters() can be NULL, and thus the related checks are added. However, in the same call stack, these variables are also used in ring_buffer_free_read_page(): tracing_buffers_release() ring_buffer_wake_waiters(iter->array_buffer->buffer) cpu_buffer = buffer->buffers[cpu] -> Add checks by previous commit ring_buffer_free_read_page(iter->array_buffer->buffer) cpu_buffer = buffer->buffers[cpu] -> No check Thus, to avod possible null-pointer derefernces, the related checks should be added. These results are reported by a static tool designed by myself. Link: https://lkml.kernel.org/r/20230113125501.760324-1-baijiaju1990@gmail.com Reported-by: TOTE Robot Signed-off-by: Jia-Ju Bai Signed-off-by: Steven Rostedt (Google) Signed-off-by: Sasha Levin --- kernel/trace/ring_buffer.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 4590556963551..58b8e8b1fea2e 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -5546,11 +5546,16 @@ EXPORT_SYMBOL_GPL(ring_buffer_alloc_read_page); */ void ring_buffer_free_read_page(struct trace_buffer *buffer, int cpu, void *data) { - struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; + struct ring_buffer_per_cpu *cpu_buffer; struct buffer_data_page *bpage = data; struct page *page = virt_to_page(bpage); unsigned long flags; + if (!buffer || !buffer->buffers || !buffer->buffers[cpu]) + return; + + cpu_buffer = buffer->buffers[cpu]; + /* If the page is still in use someplace else, we can't reuse it */ if (page_ref_count(page) > 1) goto out; -- 2.39.2