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 DCA66C7EE2F for ; Wed, 1 Mar 2023 16:32:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230025AbjCAQcc (ORCPT ); Wed, 1 Mar 2023 11:32:32 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51590 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230055AbjCAQcP (ORCPT ); Wed, 1 Mar 2023 11:32:15 -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 D77144BE91; Wed, 1 Mar 2023 08:31:13 -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 366E16142C; Wed, 1 Mar 2023 16:30:29 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D5764C433EF; Wed, 1 Mar 2023 16:30:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1677688228; bh=kH6AnnRV6w6c0S0NoITbfcwZB2dF9DDXWRuGqA3ne5s=; h=From:To:Cc:Subject:Date:From; b=cviddHCxHUIKqIa4GTxRyG2Er+gR2XwP3EUx1mzUJlb1uUURLncRjTpMOAzXixoGa BO7qI/J/1HVhwKy1QAstOl/eOFzq7SglQjmft2Tk28h1+bWjwdMbgqL3digMJx98OA LB6Kh0X5L/wZ03OfK0CM0dBZm0VqWU8Kc2PrGGfytagAD5PKuEMNWDVT7bO0UzQvTk 17+HT3L+FEAP63d8hMpM26ZlBi4fmrUS2imWbYeXhgQRZEmjmovKJlbpEANYXR4zfY 5tEaqkBTkLghCG3jXGvYAzCGXYfzDCraJOtEyYw90nbm1b7BBaioOnAZfy5LGcaiwQ N+E4L7I9bQPQQ== 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 4.14 1/3] tracing: Add NULL checks for buffer in ring_buffer_free_read_page() Date: Wed, 1 Mar 2023 11:30:23 -0500 Message-Id: <20230301163026.1303278-1-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 999dae39f12e5..a7808f8b6f56a 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -4554,11 +4554,16 @@ 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