From patchwork Mon Aug 7 22:25:14 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Hogan X-Patchwork-Id: 798925 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3xRBv15qcTz9s76 for ; Tue, 8 Aug 2017 08:25:49 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752121AbdHGWZe (ORCPT ); Mon, 7 Aug 2017 18:25:34 -0400 Received: from mailapp01.imgtec.com ([195.59.15.196]:13835 "EHLO mailapp01.imgtec.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752068AbdHGWZc (ORCPT ); Mon, 7 Aug 2017 18:25:32 -0400 Received: from HHMAIL01.hh.imgtec.org (unknown [10.100.10.19]) by Forcepoint Email with ESMTPS id A75FF17417D92; Mon, 7 Aug 2017 23:25:25 +0100 (IST) Received: from jhogan-linux.le.imgtec.org (192.168.154.110) by HHMAIL01.hh.imgtec.org (10.100.10.21) with Microsoft SMTP Server (TLS) id 14.3.294.0; Mon, 7 Aug 2017 23:25:30 +0100 From: James Hogan To: Alexei Starovoitov , Daniel Borkmann CC: , James Hogan , Steven Rostedt , Ingo Molnar , Subject: [RFC PATCH 2/2] bpf: Initialise mod[] in bpf_trace_printk Date: Mon, 7 Aug 2017 23:25:14 +0100 Message-ID: <20170807222514.24292-3-james.hogan@imgtec.com> X-Mailer: git-send-email 2.13.2 In-Reply-To: <20170807222514.24292-1-james.hogan@imgtec.com> References: <20170807222514.24292-1-james.hogan@imgtec.com> MIME-Version: 1.0 X-Originating-IP: [192.168.154.110] Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org In bpf_trace_printk(), the elements in mod[] are left uninitialised, but they are then incremented to track the width of the formats. Zero initialise the array just in case the memory contains non-zero values on entry. Fixes: 9c959c863f82 ("tracing: Allow BPF programs to call bpf_trace_printk()") Signed-off-by: James Hogan Cc: Alexei Starovoitov Cc: Daniel Borkmann Cc: Steven Rostedt Cc: Ingo Molnar Cc: netdev@vger.kernel.org --- When I checked (on MIPS32), the elements tended to have the value zero anyway (does BPF zero the stack or something clever?), so this is a purely theoretical fix. --- kernel/trace/bpf_trace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 32dcbe1b48f2..86a52857d941 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -129,7 +129,7 @@ BPF_CALL_5(bpf_trace_printk, char *, fmt, u32, fmt_size, u64, arg1, u64, arg2, u64, arg3) { bool str_seen = false; - int mod[3] = {}; + int mod[3] = { 0, 0, 0 }; int fmt_cnt = 0; u64 unsafe_addr; char buf[64];