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 BCB9E524C2; Thu, 30 Nov 2023 16:26:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="sCSkfLug" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 48D24C433C8; Thu, 30 Nov 2023 16:26:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1701361570; bh=9LXHDuM6zzw0I3lLLHbalF+ft4vUXMn+5cHwQxfCcD0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sCSkfLugr8Ay9/KXuv0PYe6z0T9JVupV1s5KU3qGXK4qjv4F0+rB+OdEkB+PJZmrO U3HwGsDdE2qDaFkjDgmO/4xzBjmxRyJ3VTLqw6Hnb5RHcFEU7KDUrO1JYC8qW8tR4F l8NBU0efCsagLbjWRuA0E54nXuD4xL9t/k2qJuTE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Stefan Haberland , =?UTF-8?q?Jan=20H=C3=B6ppner?= , Jens Axboe Subject: [PATCH 6.6 074/112] s390/dasd: protect device queue against concurrent access Date: Thu, 30 Nov 2023 16:22:01 +0000 Message-ID: <20231130162142.679539360@linuxfoundation.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20231130162140.298098091@linuxfoundation.org> References: <20231130162140.298098091@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jan Höppner commit db46cd1e0426f52999d50fa72cfa97fa39952885 upstream. In dasd_profile_start() the amount of requests on the device queue are counted. The access to the device queue is unprotected against concurrent access. With a lot of parallel I/O, especially with alias devices enabled, the device queue can change while dasd_profile_start() is accessing the queue. In the worst case this leads to a kernel panic due to incorrect pointer accesses. Fix this by taking the device lock before accessing the queue and counting the requests. Additionally the check for a valid profile data pointer can be done earlier to avoid unnecessary locking in a hot path. Cc: Fixes: 4fa52aa7a82f ("[S390] dasd: add enhanced DASD statistics interface") Reviewed-by: Stefan Haberland Signed-off-by: Jan Höppner Signed-off-by: Stefan Haberland Link: https://lore.kernel.org/r/20231025132437.1223363-3-sth@linux.ibm.com Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- drivers/s390/block/dasd.c | 24 +++++++++++++----------- 1 file changed, 13 insertions(+), 11 deletions(-) --- a/drivers/s390/block/dasd.c +++ b/drivers/s390/block/dasd.c @@ -674,18 +674,20 @@ static void dasd_profile_start(struct da * we count each request only once. */ device = cqr->startdev; - if (device->profile.data) { - counter = 1; /* request is not yet queued on the start device */ - list_for_each(l, &device->ccw_queue) - if (++counter >= 31) - break; - } + if (!device->profile.data) + return; + + spin_lock(get_ccwdev_lock(device->cdev)); + counter = 1; /* request is not yet queued on the start device */ + list_for_each(l, &device->ccw_queue) + if (++counter >= 31) + break; + spin_unlock(get_ccwdev_lock(device->cdev)); + spin_lock(&device->profile.lock); - if (device->profile.data) { - device->profile.data->dasd_io_nr_req[counter]++; - if (rq_data_dir(req) == READ) - device->profile.data->dasd_read_nr_req[counter]++; - } + device->profile.data->dasd_io_nr_req[counter]++; + if (rq_data_dir(req) == READ) + device->profile.data->dasd_read_nr_req[counter]++; spin_unlock(&device->profile.lock); }