linux-kernel - [PATCH AUTOSEL 5.4 40/52] cdrom: gdrom: initialize global variable at init time

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Message-Id: <20210524144903.2498518-40-sashal@kernel.org>
Date:   Mon, 24 May 2021 10:48:50 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Peter Rosin <peda@...ntia.se>, Jens Axboe <axboe@...nel.dk>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH AUTOSEL 5.4 40/52] cdrom: gdrom: initialize global variable at init time

From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

[ Upstream commit 9183f01b5e6e32eb3f17b5f3f8d5ad5ac9786c49 ]

As Peter points out, if we were to disconnect and then reconnect this
driver from a device, the "global" state of the device would contain odd
values and could cause problems.  Fix this up by just initializing the
whole thing to 0 at probe() time.

Ideally this would be a per-device variable, but given the age and the
total lack of users of it, that would require a lot of s/./->/g changes
for really no good reason.

Reported-by: Peter Rosin <peda@...ntia.se>
Cc: Jens Axboe <axboe@...nel.dk>
Reviewed-by: Peter Rosin <peda@...ntia.se>
Link: https://lore.kernel.org/r/YJP2j6AU82MqEY2M@kroah.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/cdrom/gdrom.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/cdrom/gdrom.c b/drivers/cdrom/gdrom.c
index 6626c84f66d1..88dc80ae0488 100644
--- a/drivers/cdrom/gdrom.c
+++ b/drivers/cdrom/gdrom.c
@@ -740,6 +740,13 @@ static const struct blk_mq_ops gdrom_mq_ops = {
 static int probe_gdrom(struct platform_device *devptr)
 {
 	int err;
+
+	/*
+	 * Ensure our "one" device is initialized properly in case of previous
+	 * usages of it
+	 */
+	memset(&gd, 0, sizeof(gd));
+
 	/* Start the device */
 	if (gdrom_execute_diagnostic() != 1) {
 		pr_warning("ATA Probe for GDROM failed\n");
@@ -843,7 +850,7 @@ static struct platform_driver gdrom_driver = {
 static int __init init_gdrom(void)
 {
 	int rc;
-	gd.toc = NULL;
+
 	rc = platform_driver_register(&gdrom_driver);
 	if (rc)
 		return rc;
-- 
2.30.2