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[209.132.180.67]) by mx.google.com with ESMTP id y73si3726735pgd.478.2018.12.14.04.14.52; Fri, 14 Dec 2018 04:15:07 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=BNWgYrhy; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732265AbeLNMOF (ORCPT + 99 others); Fri, 14 Dec 2018 07:14:05 -0500 Received: from mail.kernel.org ([198.145.29.99]:33622 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730579AbeLNMOE (ORCPT ); Fri, 14 Dec 2018 07:14:04 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 0522C214F0; Fri, 14 Dec 2018 12:14:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1544789643; bh=E3oorWNOlYDLc1kVSFU3vmYZjJsfQQUVHfMqG2SUYZM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=BNWgYrhyxXvSzB/tdMQO+TxecbbuhTiunlygICh+4RUbBxE4GHBKVTr3Gv4VhBJC6 CDoA0KKiV1VpJy03Xg96/iCVSMjN3SYhvghZH7oVG4RawSOiUH0ZQWH8m19i5ZbRys I5kYRci7rBA+zVq5NNmysRpTl35nYLcXuzH8oafA= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+1ec5c5ec949c4adaa0c4@syzkaller.appspotmail.com, Martynas Pumputis , Daniel Borkmann , Sasha Levin Subject: [PATCH 4.4 21/88] bpf: fix check of allowed specifiers in bpf_trace_printk Date: Fri, 14 Dec 2018 12:59:55 +0100 Message-Id: <20181214115703.888579559@linuxfoundation.org> X-Mailer: git-send-email 2.20.0 In-Reply-To: <20181214115702.151309521@linuxfoundation.org> References: <20181214115702.151309521@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ [ 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 4228fd3682c3..3dd40c736067 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -119,11 +119,13 @@ static u64 bpf_trace_printk(u64 r1, u64 fmt_size, u64 r3, u64 r4, u64 r5) 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; -- 2.19.1