From patchwork Mon Aug 17 15:11:29 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 265939 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=-12.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham 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 11885C433E3 for ; Mon, 17 Aug 2020 19:42:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EC4C820716 for ; Mon, 17 Aug 2020 19:42:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597693335; bh=Jptlc0QXE/ISLzp4b1//9H8rIqEhyvUeWJqL+PW7trA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=eRa7t0zYq6BfEnpaRMUG7n+4YAeioSVcDuVuuuLd6m2dDFgnr/5CK3d4stQQ+gHc+ e3PtCIdq10pH5eWRzZg8YfYrQcDN9kdC2mLZKxQmx/nGDO7aB9jTmNZ5N9/CNW6RvG Nk4uGi/50dR4W4uL4MGggyspJugA6CL4UuKlcdeg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731539AbgHQTmO (ORCPT ); Mon, 17 Aug 2020 15:42:14 -0400 Received: from mail.kernel.org ([198.145.29.99]:54744 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729339AbgHQPYY (ORCPT ); Mon, 17 Aug 2020 11:24:24 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5FA19233E2; Mon, 17 Aug 2020 15:24:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597677863; bh=Jptlc0QXE/ISLzp4b1//9H8rIqEhyvUeWJqL+PW7trA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0khGRhWu5P60XRiaLyb26j0xB+QPHRNX9fq2JjbY3AaC67rYU4jfRiwlEBUolbWzL i0BSCssfNF3r/I1PN742uJQO3WtQ3jyJ5KhpqR6yLS+R14lg1Ras96ZNokjYjefCRZ Z2fb+qNum6qjIfrpCx7Gu/phmz4EAaEH04oLqihg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Pavel Begunkov , Jens Axboe , Sasha Levin Subject: [PATCH 5.8 136/464] io_uring: fix racy overflow count reporting Date: Mon, 17 Aug 2020 17:11:29 +0200 Message-Id: <20200817143840.330114797@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200817143833.737102804@linuxfoundation.org> References: <20200817143833.737102804@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@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 d732566955d37..1d8761a9f3b88 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -7536,10 +7536,9 @@ 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