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 84B21C7EE2F for ; Wed, 1 Mar 2023 16:36:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230246AbjCAQga (ORCPT ); Wed, 1 Mar 2023 11:36:30 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60462 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229515AbjCAQgN (ORCPT ); Wed, 1 Mar 2023 11:36:13 -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 607E046094; Wed, 1 Mar 2023 08:35:24 -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 C4C776141C; Wed, 1 Mar 2023 16:30:20 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6BA87C433D2; Wed, 1 Mar 2023 16:30:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1677688220; bh=Lc2wLEVZ5PqZSCE2Szx1C7DEymrnO5bWyJZC6R2SqL4=; h=From:To:Cc:Subject:Date:From; b=rX8PMzA3VZGBIF0c+PfvTmLqErOeKDFKpzVXCpYgZ/8LwTXfYiqk3bb+gHZHf4SdC iSU13+WqutbMeGFABIxFiJZ3PEnuk7B6+TY4lfaZXSfkh9HYMtio188omYM6BXqSG9 BoJCGvpUPBGw9u4/zQph9Vc77Yt6l9cQTG8aZ4JTsb4IdnnunrtT2cpTaPi4hhCxQO mv8IRtKflXtEZlMOD48UXXBqXq8QokW0/fxMk/sVxSy/7b4wZehLDNP4aOP6OnU45a VHVzkuRcX3X9sS8eXnh4g3U6KAlnWbboVRZUV1jOAOm+/LrLgXxVRBg48auWJZX2nX j2nX3Sgp0ft5w== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Jia-Ju Bai , TOTE Robot , Steven Rostedt , Sasha Levin , mhiramat@kernel.org, linux-trace-kernel@vger.kernel.org Subject: [PATCH AUTOSEL 4.19 1/3] tracing: Add NULL checks for buffer in ring_buffer_free_read_page() Date: Wed, 1 Mar 2023 11:30:15 -0500 Message-Id: <20230301163017.1303229-1-sashal@kernel.org> X-Mailer: git-send-email 2.39.2 MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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 5e5b0c067f611..bef3d01b8ff61 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -4685,11 +4685,16 @@ EXPORT_SYMBOL_GPL(ring_buffer_alloc_read_page); */ void ring_buffer_free_read_page(struct ring_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