From patchwork Wed Dec 5 09:46:41 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sasha Levin X-Patchwork-Id: 1008090 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@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=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=kernel.org Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.b="2hqCN5CE"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 438vPV6dB5z9s1c for ; Wed, 5 Dec 2018 21:00:46 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729624AbeLEJuC (ORCPT ); Wed, 5 Dec 2018 04:50:02 -0500 Received: from mail.kernel.org ([198.145.29.99]:56224 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729617AbeLEJuB (ORCPT ); Wed, 5 Dec 2018 04:50:01 -0500 Received: from sasha-vm.mshome.net (unknown [213.57.143.11]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 270E2213A2; Wed, 5 Dec 2018 09:49:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1544003400; bh=qHcYHsQPPA1K6C+5HwlYTMEiraOxiID9WooPkQCi9Ns=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=2hqCN5CExVq20eoVh6khvX670raj+BxkXYeHtka+gf+zuC2KjbaDmM+SCPWKQTB0r QokF8gURxP/1oUxsxnXQHB3SKZEnTSGl6Hesx57MIuMfimos7BXqHxKVOVnzM2p4xW c7g2xK5B1q0TTZmqpT4ijjUrEjMBqtXmvzs/CElM= From: Sasha Levin To: stable@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Martynas Pumputis , Daniel Borkmann , Sasha Levin , netdev@vger.kernel.org Subject: [PATCH AUTOSEL 4.9 20/45] bpf: fix check of allowed specifiers in bpf_trace_printk Date: Wed, 5 Dec 2018 04:46:41 -0500 Message-Id: <20181205094706.7225-20-sashal@kernel.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181205094706.7225-1-sashal@kernel.org> References: <20181205094706.7225-1-sashal@kernel.org> Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Martynas Pumputis [ Upstream commit 1efb6ee3edea57f57f9fb05dba8dcb3f7333f61f ] A format string consisting of "%p" or "%s" followed by an invalid specifier (e.g. "%p%\n" or "%s%") could pass the check which would make format_decode (lib/vsprintf.c) to warn. Fixes: 9c959c863f82 ("tracing: Allow BPF programs to call bpf_trace_printk()") Reported-by: syzbot+1ec5c5ec949c4adaa0c4@syzkaller.appspotmail.com Signed-off-by: Martynas Pumputis Signed-off-by: Daniel Borkmann Signed-off-by: Sasha Levin --- kernel/trace/bpf_trace.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 41805fb3c661..7cc06f267be5 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -161,11 +161,13 @@ BPF_CALL_5(bpf_trace_printk, char *, fmt, u32, fmt_size, u64, arg1, i++; } else if (fmt[i] == 'p' || fmt[i] == 's') { mod[fmt_cnt]++; - i++; - if (!isspace(fmt[i]) && !ispunct(fmt[i]) && fmt[i] != 0) + /* disallow any further format extensions */ + if (fmt[i + 1] != 0 && + !isspace(fmt[i + 1]) && + !ispunct(fmt[i + 1])) return -EINVAL; fmt_cnt++; - if (fmt[i - 1] == 's') { + if (fmt[i] == 's') { if (str_seen) /* allow only one '%s' per fmt string */ return -EINVAL;