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=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT,USER_IN_DEF_DKIM_WL 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 82909C433EF for ; Mon, 13 Sep 2021 18:38:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6AF67610A2 for ; Mon, 13 Sep 2021 18:38:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241450AbhIMSjX (ORCPT ); Mon, 13 Sep 2021 14:39:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47534 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347169AbhIMSjV (ORCPT ); Mon, 13 Sep 2021 14:39:21 -0400 Received: from mail-pl1-x649.google.com (mail-pl1-x649.google.com [IPv6:2607:f8b0:4864:20::649]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AB449C061574 for ; Mon, 13 Sep 2021 11:38:05 -0700 (PDT) Received: by mail-pl1-x649.google.com with SMTP id x5-20020a1709028ec500b0013a347b89e4so3623140plo.3 for ; Mon, 13 Sep 2021 11:38:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:message-id:mime-version:subject:from:to:cc; bh=ORusbr9BmjXcPtqf7j3wkWSVtlEx7sQaXqjNFhLLsiA=; b=Uxvo/AAaVm/TrsvJp2gPNfsdMAsdNAIFJblX2JLeH8VzGnDWWDFSFoA9yWUkSSpMiz cGjKsie76v7gq+aIUvGk1bAoiZcDZQj8NQMlSNL6WGp60sBlfLD8FFHehC1QkZ7n/cv9 PT0kSVMrvv3dHZPO/o8Io+O2gZZTfKgfls4OVc22DWixMDPGZAqRdlFDNet11tfAs7e/ +4BNQQ2J7H5VMxHr4pQEGJ7ClSfgfoxNGYKCP4n61HRZ8AKVqUg6NB6Iw+a55vNnA1ny VdH7D84V1kTI01XOVAgWHojt+9WSLUB2aiI/aliBL3hdIgK4TRKRr3uUHHeQNchu9Qal MoZA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=ORusbr9BmjXcPtqf7j3wkWSVtlEx7sQaXqjNFhLLsiA=; b=mxQigjFSn63vS8zQMQgQzTcVpj2+yJQRPt658YxfmWy6lpM1bEg5PrMCZ4JrMrvD+R hFUsqWk0tVtr0E9gd4CphzyFwfpcy5kuLwwDvglACftC4JCQH5VzMrWhXnT390Me65/M G0S8Jkcv0BZQQLDLqbcpsJkDtsVZq7d1E+5Kul4qpj/y+3oaoNxqE7AKpQkgUDgEGNzk mXF5Dn74FLOqADTmlQRMBoabjujLQ4SsQ3u4EIeLHzmJPcqiSbDJV3JmNw0iVJJxbgFY 5X5wIXmJ5VsZZp57Y02zHiqmlro0Kq0m1zL9pNa87K1hO4XfXAm8gjCePu7xrmkNktox AbTw== X-Gm-Message-State: AOAM531knTX/tDBt+njZf2vxd+PISoWwTJpzdaeCnMWEb0e1fo+19/l9 /NN2f7/Hn8pzM+Q/T0uEjZqn+MPFOb62Ppw= X-Google-Smtp-Source: ABdhPJyjtH0D7FayRsBKsENe5kjIx+9tqfBFSgR2CE2IKyePXWGrlsCUJovbx0HZTl6n38vb3KkdnSnzJdwn0u0= X-Received: from ramjiyani.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:2edd]) (user=ramjiyani job=sendgmr) by 2002:a17:90a:7f04:: with SMTP id k4mr1046505pjl.0.1631558284830; Mon, 13 Sep 2021 11:38:04 -0700 (PDT) Date: Mon, 13 Sep 2021 18:37:52 +0000 Message-Id: <20210913183753.563103-1-ramjiyani@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.33.0.309.g3052b89438-goog Subject: [PATCH] aio: Add support for the POLLFREE From: Ramji Jiyani To: Alexander Viro , Benjamin LaHaise , Arnd Bergmann Cc: Ramji Jiyani , kernel-team@android.com, linux-fsdevel@vger.kernel.org, linux-aio@kvack.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit f5cb779ba163 ("ANDROID: binder: remove waitqueue when thread exits.") fixed the use-after-free in eventpoll but aio still has the same issue because it doesn't honor the POLLFREE flag. Add support for the POLLFREE flag to force complete iocb inline in aio_poll_wake(). A thread may use it to signal it's exit and/or request to cleanup while pending poll request. In this case, aio_poll_wake() needs to make sure it doesn't keep any reference to the queue entry before returning from wake to avoid possible use after free via poll_cancel() path. The POLLFREE flag is no more exclusive to the epoll and is being shared with the aio. Remove comment from poll.h to avoid confusion. Also enclosed the POLLFREE macro definition in parentheses to fix checkpatch error. Signed-off-by: Ramji Jiyani --- fs/aio.c | 45 ++++++++++++++++++--------------- include/uapi/asm-generic/poll.h | 2 +- 2 files changed, 26 insertions(+), 21 deletions(-) diff --git a/fs/aio.c b/fs/aio.c index 51b08ab01dff..5d539c05df42 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -1674,6 +1674,7 @@ static int aio_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync, { struct poll_iocb *req = container_of(wait, struct poll_iocb, wait); struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll); + struct kioctx *ctx = iocb->ki_ctx; __poll_t mask = key_to_poll(key); unsigned long flags; @@ -1683,29 +1684,33 @@ static int aio_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync, list_del_init(&req->wait.entry); - if (mask && spin_trylock_irqsave(&iocb->ki_ctx->ctx_lock, flags)) { - struct kioctx *ctx = iocb->ki_ctx; + /* + * Use irqsave/irqrestore because not all filesystems (e.g. fuse) + * call this function with IRQs disabled and because IRQs have to + * be disabled before ctx_lock is obtained. + */ + if (mask & POLLFREE) { + /* Force complete iocb inline to remove refs to deleted entry */ + spin_lock_irqsave(&ctx->ctx_lock, flags); + } else if (!(mask && spin_trylock_irqsave(&ctx->ctx_lock, flags))) { + /* Can't complete iocb inline; schedule for later */ + schedule_work(&req->work); + return 1; + } - /* - * Try to complete the iocb inline if we can. Use - * irqsave/irqrestore because not all filesystems (e.g. fuse) - * call this function with IRQs disabled and because IRQs - * have to be disabled before ctx_lock is obtained. - */ - list_del(&iocb->ki_list); - iocb->ki_res.res = mangle_poll(mask); - req->done = true; - if (iocb->ki_eventfd && eventfd_signal_allowed()) { - iocb = NULL; - INIT_WORK(&req->work, aio_poll_put_work); - schedule_work(&req->work); - } - spin_unlock_irqrestore(&ctx->ctx_lock, flags); - if (iocb) - iocb_put(iocb); - } else { + /* complete iocb inline */ + list_del(&iocb->ki_list); + iocb->ki_res.res = mangle_poll(mask); + req->done = true; + if (iocb->ki_eventfd && eventfd_signal_allowed()) { + iocb = NULL; + INIT_WORK(&req->work, aio_poll_put_work); schedule_work(&req->work); } + spin_unlock_irqrestore(&ctx->ctx_lock, flags); + if (iocb) + iocb_put(iocb); + return 1; } diff --git a/include/uapi/asm-generic/poll.h b/include/uapi/asm-generic/poll.h index 41b509f410bf..35b1b69af729 100644 --- a/include/uapi/asm-generic/poll.h +++ b/include/uapi/asm-generic/poll.h @@ -29,7 +29,7 @@ #define POLLRDHUP 0x2000 #endif -#define POLLFREE (__force __poll_t)0x4000 /* currently only for epoll */ +#define POLLFREE ((__force __poll_t)0x4000) #define POLL_BUSY_LOOP (__force __poll_t)0x8000 -- 2.33.0.309.g3052b89438-goog