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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7FF53EB64DD for ; Sun, 2 Jul 2023 19:41:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231695AbjGBTlX (ORCPT ); Sun, 2 Jul 2023 15:41:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53310 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231639AbjGBTlB (ORCPT ); Sun, 2 Jul 2023 15:41:01 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A7BDA1BD2; Sun, 2 Jul 2023 12:40:33 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 865BA60C8D; Sun, 2 Jul 2023 19:40:33 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4573AC433C9; Sun, 2 Jul 2023 19:40:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1688326832; bh=pmq9JZD8yIqmj0mM5w5/RCcJ+BTdxiwpEgcufDWTT6Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=BQki/MMrdl//CtUgjlb6u6dGjrcIwNJRZOXWdT0JOzXghHb5V085i8EoJBGA97xTb xkRXtAqKnsRGTpcQy69FyRpWp3JivubxbVHgYTZdbKLvncbD/6e2P572GLV4gJrrYr /RRanFv+B48At0kOqMzdokksF0oam4KPx8EHFNuo7Sw1AvELMRp6uBOA92FedAjcDx NOOt/W0MU07O0ldMuwc75eYTcT8I0LVJIzi2WKqhhDyqj+QZg98+dbdhVA1x7mvtq6 aDJQYQ57wfBGgy/kqjAFMkMzpfJWlUeyfmY0K5b2qZP1c/RWhQZK/A4T2iAs9HLMqu Tnnv84lN4kZ1w== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Pavel Begunkov , syzbot+cb265db2f3f3468ef436@syzkaller.appspotmail.com, Jens Axboe , Sasha Levin , io-uring@vger.kernel.org Subject: [PATCH AUTOSEL 6.4 03/15] io_uring: annotate offset timeout races Date: Sun, 2 Jul 2023 15:40:08 -0400 Message-Id: <20230702194020.1776895-3-sashal@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230702194020.1776895-1-sashal@kernel.org> References: <20230702194020.1776895-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.4.1 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org From: Pavel Begunkov [ Upstream commit 5498bf28d8f2bd63a46ad40f4427518615fb793f ] It's racy to read ->cached_cq_tail without taking proper measures (usually grabbing ->completion_lock) as timeout requests with CQE offsets do, however they have never had a good semantics for from when they start counting. Annotate racy reads with data_race(). Reported-by: syzbot+cb265db2f3f3468ef436@syzkaller.appspotmail.com Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/r/4de3685e185832a92a572df2be2c735d2e21a83d.1684506056.git.asml.silence@gmail.com Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- io_uring/timeout.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/io_uring/timeout.c b/io_uring/timeout.c index fc950177e2e1d..350eb830b4855 100644 --- a/io_uring/timeout.c +++ b/io_uring/timeout.c @@ -594,7 +594,7 @@ int io_timeout(struct io_kiocb *req, unsigned int issue_flags) goto add; } - tail = ctx->cached_cq_tail - atomic_read(&ctx->cq_timeouts); + tail = data_race(ctx->cached_cq_tail) - atomic_read(&ctx->cq_timeouts); timeout->target_seq = tail + off; /* Update the last seq here in case io_flush_timeouts() hasn't. -- 2.39.2