Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9F807C636D7 for ; Mon, 13 Feb 2023 04:28:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229644AbjBME2U (ORCPT ); Sun, 12 Feb 2023 23:28:20 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40894 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229472AbjBME2S (ORCPT ); Sun, 12 Feb 2023 23:28:18 -0500 Received: from wout2-smtp.messagingengine.com (wout2-smtp.messagingengine.com [64.147.123.25]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3C2176596; Sun, 12 Feb 2023 20:28:17 -0800 (PST) Received: from compute2.internal (compute2.nyi.internal [10.202.2.46]) by mailout.west.internal (Postfix) with ESMTP id 1A5C432004CE; Sun, 12 Feb 2023 23:28:14 -0500 (EST) Received: from mailfrontend1 ([10.202.2.162]) by compute2.internal (MEProxy); Sun, 12 Feb 2023 23:28:14 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=themaw.net; h=cc :cc:content-transfer-encoding:content-type:date:date:from:from :in-reply-to:in-reply-to:message-id:mime-version:references :reply-to:sender:subject:subject:to:to; s=fm3; t=1676262493; x= 1676348893; bh=0i5TurBb3X4wdi823xN8BxjMRfYoHg+NNXP0jPnU5RY=; b=e FGdztbJWaVqSFr0mK4refTYRRpk4q1isnVhU+a10fSwuznf9R7HpMkKA3V42MBWx OVr4pK3HwUKA/91K8bJUIb9pTD2dgyCRISJoCJ8s7fuPK50oL2iYsrvuuS6mXDP6 3hNfpO/sAKTGDn8hocvT86NSo4q4Ni4Zjaeo0rCJfxpSUOOF9kViStbCiIbBDhVa 5AvFnq8+XA2K4xVMuf3UWrjZBj/cmLa5L4H/gA+DQhCPiabA9hjwJM6NCjs/wMzl xRmo9RGGfFHfOAUTmk/UA4vgSgMw0g8j8gyx6rGEbZSlJB6ksYEkL6N7eGa0RpvO 7iFKEA6W0VOcCIAizuJ8A== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-transfer-encoding :content-type:date:date:feedback-id:feedback-id:from:from :in-reply-to:in-reply-to:message-id:mime-version:references :reply-to:sender:subject:subject:to:to:x-me-proxy:x-me-proxy :x-me-sender:x-me-sender:x-sasl-enc; s=fm1; t=1676262493; x= 1676348893; bh=0i5TurBb3X4wdi823xN8BxjMRfYoHg+NNXP0jPnU5RY=; b=q mjrCA4TVAt3+EyqMOC3MDxZuXOGpbS3CCjhD+kpugy90P4BHABs1FD8VRZYThcPv Obp5KsVSLyGfQvGl31t199TYXsX7apvnVTuekn1etjzKk+51ZoiHfQ0E634jebgX XjHGHKhD2dRIpbOrT/jF1VKFoz98BEh2LXn3y7yQPaJ2HhqTXyzeXOomnVBBchtX XD1G8kyzbdK1WDscgIn3RHrDvuSquAA30kYB9QVRYfAl0D1TVtvt9Jrz9a2/gyQF jbuEjlsMFG1x/uejZk3eD3FhR9/R7BLWpV+ibNpxU/lYJIOMP08anhvtrrL3qIkk w6cOgVxN8ybRZGe2WgnMw== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvhedrudeitddgjedtucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhepkfffgggfuffvvehfhfgjtgfgsehtjeertddtfeejnecuhfhrohhmpefkrghn ucfmvghnthcuoehrrghvvghnsehthhgvmhgrfidrnhgvtheqnecuggftrfgrthhtvghrnh epuefhueeiieejueevkefgiedtteehgfdutdelfffhleeflefhudeuvdefhfeghfehnecu vehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehmrghilhhfrhhomheprhgrvhgvnh esthhhvghmrgifrdhnvght X-ME-Proxy: Feedback-ID: i31e841b0:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Sun, 12 Feb 2023 23:28:00 -0500 (EST) Message-ID: <5b86f03b-020b-1584-be8f-b7dc7277fa0a@themaw.net> Date: Mon, 13 Feb 2023 12:27:55 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.6.0 Subject: Re: [PATCH 0/1] autofs: fix memory leak of waitqueues in autofs_catatonic_mode Content-Language: en-US To: Fedor Pchelkin Cc: Matthew Wilcox , Andrei Vagin , Takeshi Misawa , autofs@vger.kernel.org, linux-kernel@vger.kernel.org, Alexey Khoroshilov , lvc-project@linuxtesting.org References: <20230211195950.452364-1-pchelkin@ispras.ru> From: Ian Kent In-Reply-To: <20230211195950.452364-1-pchelkin@ispras.ru> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/2/23 03:59, Fedor Pchelkin wrote: > Syzkaller reports the leak [1]. It is reproducible. > > The following patch fixes the leak. It was proposed by Takeshi Misawa and > tested by Syzbot. > > In other places of the code the waitqueue is freed when its wait_ctr > becomes zero (see autofs_wait_release). So I think it is not actually > supposed that inside autofs_catatonic_mode wait_ctr cannot be decreased to > zero. Please correct me if I'm wrong. This is a bit had to read but I think your saying there's an assumption that wait_ctr can't become zero in autofs_catatonic_mode(). That's correct, the case of a waiting process getting sent a signal is not accounted for and this can (as you observed) lead to the wait not being freed and also not being freed at umount. I think the change here should be sufficient to resolve the leak and I can't think of any cases where this could cause a further problem. > > Also, looking at the discussion [2] of the '[PATCH] autofs4: use wake_up() > instead of wake_up_interruptible', shouldn't wake_up_interruptible() > inside autofs_catatonic_mode() be replaced with wake_up()? This does imply that [2] should have been applied to autofs_catatonic_mode() as well, I'm still trying to grok if that change would cause side effects for the change here but I think not. Ian