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=-13.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 90F37C433DF for ; Mon, 10 Aug 2020 19:30:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5ECAF22BEA for ; Mon, 10 Aug 2020 19:30:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597087842; bh=B7pz3A/RGxlVPXqUbuyVNgpNuReQn/DdqP+RwKMq5vo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=z1jiuqp4jNzYjgLXCyUfsUlF/D1HraeLXaDfJ2IPQmEq4jISHY4vzzSwE14h5EG1Q 8xI2+qV6Prh3/fTskhXpqC3BnH/LkkAQ9JYJtPp4zFQxqtS4QXPIs8VTkfzwiHn03+ E1lq1DmfB3YipaugtMobGBejD7XYGbdnjqcO0HIE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728835AbgHJTal (ORCPT ); Mon, 10 Aug 2020 15:30:41 -0400 Received: from mail.kernel.org ([198.145.29.99]:37608 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728922AbgHJTKX (ORCPT ); Mon, 10 Aug 2020 15:10:23 -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 E7FDC22B47; Mon, 10 Aug 2020 19:10:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597086622; bh=B7pz3A/RGxlVPXqUbuyVNgpNuReQn/DdqP+RwKMq5vo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PiYnedJVx/Eu7fcr+nuZ2pfgM5io3xIT0SkSFNRgMhAWpxSEnzYxUd0rjYm6/jfvC t1yNtc7m09ScS6ev2bS7Z00uxoeX76b0Z3KzLCbBMHaoQrVJk7X0kbFw+E5hBiGJMD iTTLytYWZFngBvmpfGkCBDXd2wL6mppJwJWqzFPE= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Pavel Begunkov , Jens Axboe , Sasha Levin , io-uring@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: [PATCH AUTOSEL 5.8 61/64] io_uring: fix racy overflow count reporting Date: Mon, 10 Aug 2020 15:08:56 -0400 Message-Id: <20200810190859.3793319-61-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200810190859.3793319-1-sashal@kernel.org> References: <20200810190859.3793319-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Pavel Begunkov [ Upstream commit b2bd1cf99f3e7c8fbf12ea07af2c6998e1209e25 ] All ->cq_overflow modifications should be under completion_lock, otherwise it can report a wrong number to the userspace. Fix it in io_uring_cancel_files(). Signed-off-by: Pavel Begunkov Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- fs/io_uring.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index acd98df1f7d44..73f5e0a9bf2bd 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -7529,10 +7529,9 @@ static void io_uring_cancel_files(struct io_ring_ctx *ctx, clear_bit(0, &ctx->cq_check_overflow); ctx->rings->sq_flags &= ~IORING_SQ_CQ_OVERFLOW; } - spin_unlock_irq(&ctx->completion_lock); - WRITE_ONCE(ctx->rings->cq_overflow, atomic_inc_return(&ctx->cached_cq_overflow)); + spin_unlock_irq(&ctx->completion_lock); /* * Put inflight ref and overflow ref. If that's -- 2.25.1