From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-639720-1527104105-2-14620573317030317425 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.248, MAILING_LIST_MULTI -1, RCVD_IN_DNSWL_HI -5, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='US', FromHeader='de', MailFrom='org' X-Spam-charsets: X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: linux-api-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=fm2; t= 1527104104; b=U9iM8fS9whfXO/kcm/Ui9qgtGuxPDdqIMN5VIRyfioA4zfa2PK xsCA0eM34bQ5Ek9fCPwIw6F/ErUmjNngqKAys5IWJZ0RmnAovk5xA9oKh7Rfft9F yi/NCdYEr+iE1t1Zxr419Vl9Y91Lzq0EKSpi8j7bH5CFblOi5MQG2nurLK2B5zbO FdCN0ZSz1ilbOvfIbCs3taQ7ReDZp/t2OTXv5vTTdcBzzeEdPv0oCILdcChXncQD wX8C1gQFm4R9BBHNK91FLJVe0k8IsNJhXlOgTipYvRt1qO5AYLBjDib72vwE0uME W8RVl0c3PG8Vs9+ehz6R9phvhY89KYzNGyiw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=from:to:cc:subject:date:message-id :in-reply-to:references:sender:list-id; s=fm2; t=1527104104; bh= 9uJ/9rkyQkHxVxsxFFs+avSoniZM4kOrtCAaQkrMDb0=; b=heUDMDOzJzRvm2xj NrUCpGXxybRppWvBROFGl59r2a7iPzPwKZgfE6hy3oc+8Wji/XATEctLgJhy014T szGtiT9HLJg9aglVQSiaNvlkTKnp6/oUiK7QSxux2CiGMBeISOYaQIleNc1pSB0d +kzeFNgpi30Q3uxJEu/sy8EOdMuextRkdjx+8u+GS+fmoR34qNDFV5rAkRJVGSKb Wc+6eFrJAifWj7fXGdhMMubFO51sVPK2IODtx7GSCxngRCthGUYMQC1SoIk+gAJY 6eYr4HiGht6DS48YCQO9zMwVocG18eYkkSuxSWbL8e4lDQ9aL+mgL0SMOAJA/V82 vLl0mg== ARC-Authentication-Results: i=1; mx6.messagingengine.com; arc=none (no signatures found); dkim=fail (message has been altered, 2048-bit rsa key sha256) header.d=infradead.org header.i=@infradead.org header.b=uILGLEP9 x-bits=2048 x-keytype=rsa x-algorithm=sha256 x-selector=bombadil.20170209; dmarc=none (p=none,has-list-id=yes,d=none) header.from=lst.de; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=linux-api-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-cm=none score=0; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=lst.de header.result=pass header_is_org_domain=yes; x-vs=clean score=0 state=0 Authentication-Results: mx6.messagingengine.com; arc=none (no signatures found); dkim=fail (message has been altered, 2048-bit rsa key sha256) header.d=infradead.org header.i=@infradead.org header.b=uILGLEP9 x-bits=2048 x-keytype=rsa x-algorithm=sha256 x-selector=bombadil.20170209; dmarc=none (p=none,has-list-id=yes,d=none) header.from=lst.de; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=linux-api-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-cm=none score=0; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=lst.de header.result=pass header_is_org_domain=yes; x-vs=clean score=0 state=0 X-ME-VSCategory: clean X-CM-Envelope: MS4wfIU8+abt9T2RxlXtdIUhUPfXobSK4TURAgk81XVOg6h57jePYWO2++yDTJfXVBHN534GAoGANXMhucKzq2DCXbFkIKNJj3ufoxBRZi5gHu2gWSQZrMO5 0cYifVgsKwGFDrkTjqaNFmLj0ojVmKZcuHpc6aIQtb8xAhyhiYswBTh62bysD+Mjj9b2zhG5l6Dnc5HRiMOCHpfmGeaU5wSe2s/VO5lGjL0i2ZSVxqxVr6as X-CM-Analysis: v=2.3 cv=FKU1Odgs c=1 sm=1 tr=0 a=UK1r566ZdBxH71SXbqIOeA==:117 a=UK1r566ZdBxH71SXbqIOeA==:17 a=VUJBJC2UJ8kA:10 a=drOt6m5kAAAA:8 a=VwQbUJbxAAAA:8 a=32GxPdB41DALxrjWDjkA:9 a=ZIexoJY8WHTOOgZQ:21 a=xH4ctsHu6irhgxCo:21 a=x8gzFH9gYPwA:10 a=RMMjzBEyIzXRtoq5n5K6:22 a=AjGcO6oz07-iQ99wixmX:22 X-ME-CMScore: 0 X-ME-CMCategory: none Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934282AbeEWTUe (ORCPT ); Wed, 23 May 2018 15:20:34 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:40654 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934256AbeEWTU3 (ORCPT ); Wed, 23 May 2018 15:20:29 -0400 From: Christoph Hellwig To: viro@zeniv.linux.org.uk Cc: Avi Kivity , linux-aio@kvack.org, linux-fsdevel@vger.kernel.org, netdev@vger.kernel.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, stable@kernel.org Subject: [PATCH 01/33] fix io_destroy()/aio_complete() race Date: Wed, 23 May 2018 21:19:50 +0200 Message-Id: <20180523192022.1703-2-hch@lst.de> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180523192022.1703-1-hch@lst.de> References: <20180523192022.1703-1-hch@lst.de> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-api-owner@vger.kernel.org X-Mailing-List: linux-api@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: From: Al Viro If io_destroy() gets to cancelling everything that can be cancelled and gets to kiocb_cancel() calling the function driver has left in ->ki_cancel, it becomes vulnerable to a race with IO completion. At that point req is already taken off the list and aio_complete() does *NOT* spin until we (in free_ioctx_users()) releases ->ctx_lock. As the result, it proceeds to kiocb_free(), freing req just it gets passed to ->ki_cancel(). Fix is simple - remove from the list after the call of kiocb_cancel(). All instances of ->ki_cancel() already have to cope with the being called with iocb still on list - that's what happens in io_cancel(2). Cc: stable@kernel.org Fixes: 0460fef2a921 "aio: use cancellation list lazily" Signed-off-by: Al Viro Signed-off-by: Christoph Hellwig --- fs/aio.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/fs/aio.c b/fs/aio.c index 755d3f57bcc8..1c383bb44b2d 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -639,9 +639,8 @@ static void free_ioctx_users(struct percpu_ref *ref) while (!list_empty(&ctx->active_reqs)) { req = list_first_entry(&ctx->active_reqs, struct aio_kiocb, ki_list); - - list_del_init(&req->ki_list); kiocb_cancel(req); + list_del_init(&req->ki_list); } spin_unlock_irq(&ctx->ctx_lock); -- 2.17.0