From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3FA0B881F for ; Fri, 10 Mar 2023 14:42:19 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6F37AC433D2; Fri, 10 Mar 2023 14:42:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1678459339; bh=uCECDDvtpiSYIrsHG/STdok+YOIBt6dmLdPwrNFmHSc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=SzVJ8jy96QlxHlZMScHpFktOh+wFQjnTRajyJ9+nnHB+RC4mVX7hhbBEMyh/8Gw8e sG0aHXoO939qqsZtfstGwnhTspBl6ygFKmhULGkNrvmM7KhfzH1FQRU6SSrqQOK0OC ZvXhAib2DXp7rqPPNwxnKVQ9emwXVpz0r++aJLhA= 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 5.4 329/357] tracing: Add NULL checks for buffer in ring_buffer_free_read_page() Date: Fri, 10 Mar 2023 14:40:18 +0100 Message-Id: <20230310133749.169849158@linuxfoundation.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230310133733.973883071@linuxfoundation.org> References: <20230310133733.973883071@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 11e8189dd8ae9..58809fffc8171 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -4769,11 +4769,16 @@ 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