From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C890C168B7 for ; Wed, 9 Aug 2023 10:56:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 48DE4C433C8; Wed, 9 Aug 2023 10:56:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1691578577; bh=99FFulc56JrjsOEdxJ3eqkAbwiq9JSrJY6rpjMxyMnw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Y2GEKjDaLOZ1oitKbGha6qslQHSZOF4TxoLR521dqOyFfvi9odE3ffnHisxEj0zHA 4GZq/Xlsqn9n20crp+6V/RaFfiBPoSqRexk8GeN6Wur0kAmfsjHlmQiCYHN8SdcxKd Xd0fgrqoSi9NZ2ElMkmCIhS9DCfbx6p1d2bS1yZA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+cb265db2f3f3468ef436@syzkaller.appspotmail.com, Pavel Begunkov , Jens Axboe Subject: [PATCH 6.1 110/127] io_uring: annotate offset timeout races Date: Wed, 9 Aug 2023 12:41:37 +0200 Message-ID: <20230809103640.255389752@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230809103636.615294317@linuxfoundation.org> References: <20230809103636.615294317@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Pavel Begunkov commit 5498bf28d8f2bd63a46ad40f4427518615fb793f upstream. 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: Greg Kroah-Hartman --- io_uring/timeout.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/io_uring/timeout.c +++ b/io_uring/timeout.c @@ -545,7 +545,7 @@ int io_timeout(struct io_kiocb *req, uns 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.