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 X-Spam-Level: X-Spam-Status: No, score=-9.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DA0D2C4360F for ; Wed, 27 Mar 2019 19:11:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AAEDA2064A for ; Wed, 27 Mar 2019 19:11:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553713877; bh=EEaZFz9zlsIZ7fAQBlx070X5SA2PFqLMkh+kUaNIyuI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=1QKVbn4OolGSqXQSG2kvrzYQ10qKAncPuaEwcu15FiITkNjSFFcZTa5D+p9czczwi P6bW3CRCIJH4Lgz99cXaCtr0c6QGqoSFsXVbpnKFWdR0DCAso+QdVjuVCtagQSG3mT xOu4jktu/nKwbyrygl4xZ6NGEXGh3QuIb0AyNx3o= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388220AbfC0SKq (ORCPT ); Wed, 27 Mar 2019 14:10:46 -0400 Received: from mail.kernel.org ([198.145.29.99]:52842 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388363AbfC0SKp (ORCPT ); Wed, 27 Mar 2019 14:10:45 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (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 E554321738; Wed, 27 Mar 2019 18:10:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553710244; bh=EEaZFz9zlsIZ7fAQBlx070X5SA2PFqLMkh+kUaNIyuI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rJp9cWUcd5KDcnKDOZ8D88RW0X9edBtzAre4v1k6xZx4QmD3VMQbq+CEzIjKK9kPc WuH+H2UJDC6rjRyoKr4x8k6ahIPu6NuMDdOEFf1zl3ZpCQdpB11bbqrEtBJcw1CNiT fd56Nhrf8Nu7Md3n8hBi8tPy2mgDFvc9Hvh05K4s= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Christian Brauner , Alexey Dobriyan , Al Viro , Dominik Brodowski , "Eric W. Biederman" , Joe Lawrence , Luis Chamberlain , Waiman Long , Andrew Morton , Linus Torvalds , Sasha Levin , linux-fsdevel@vger.kernel.org Subject: [PATCH AUTOSEL 4.19 012/192] sysctl: handle overflow for file-max Date: Wed, 27 Mar 2019 14:07:24 -0400 Message-Id: <20190327181025.13507-12-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190327181025.13507-1-sashal@kernel.org> References: <20190327181025.13507-1-sashal@kernel.org> MIME-Version: 1.0 X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org From: Christian Brauner [ Upstream commit 32a5ad9c22852e6bd9e74bdec5934ef9d1480bc5 ] Currently, when writing echo 18446744073709551616 > /proc/sys/fs/file-max /proc/sys/fs/file-max will overflow and be set to 0. That quickly crashes the system. This commit sets the max and min value for file-max. The max value is set to long int. Any higher value cannot currently be used as the percpu counters are long ints and not unsigned integers. Note that the file-max value is ultimately parsed via __do_proc_doulongvec_minmax(). This function does not report error when min or max are exceeded. Which means if a value largen that long int is written userspace will not receive an error instead the old value will be kept. There is an argument to be made that this should be changed and __do_proc_doulongvec_minmax() should return an error when a dedicated min or max value are exceeded. However this has the potential to break userspace so let's defer this to an RFC patch. Link: http://lkml.kernel.org/r/20190107222700.15954-3-christian@brauner.io Signed-off-by: Christian Brauner Acked-by: Kees Cook Cc: Alexey Dobriyan Cc: Al Viro Cc: Dominik Brodowski Cc: "Eric W. Biederman" Cc: Joe Lawrence Cc: Luis Chamberlain Cc: Waiman Long [christian@brauner.io: v4] Link: http://lkml.kernel.org/r/20190210203943.8227-3-christian@brauner.io Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- kernel/sysctl.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 3b86acd5de4e..9e22660153ff 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -126,6 +126,7 @@ static int __maybe_unused one = 1; static int __maybe_unused two = 2; static int __maybe_unused four = 4; static unsigned long one_ul = 1; +static unsigned long long_max = LONG_MAX; static int one_hundred = 100; static int one_thousand = 1000; #ifdef CONFIG_PRINTK @@ -1695,6 +1696,8 @@ static struct ctl_table fs_table[] = { .maxlen = sizeof(files_stat.max_files), .mode = 0644, .proc_handler = proc_doulongvec_minmax, + .extra1 = &zero, + .extra2 = &long_max, }, { .procname = "nr_open", -- 2.19.1