linux-kernel - [PATCH 5.11 387/601] ataflop: fix off by one in ataflop

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Date:   Wed, 12 May 2021 16:47:44 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, kernel test robot <lkp@...el.com>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Christoph Hellwig <hch@....de>, Jens Axboe <axboe@...nel.dk>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.11 387/601] ataflop: fix off by one in ataflop_probe()

From: Dan Carpenter <dan.carpenter@...cle.com>

[ Upstream commit b777f4c47781df6b23e3f4df6fdb92d9aceac7bb ]

Smatch complains that the "type > NUM_DISK_MINORS" should be >=
instead of >.  We also need to subtract one from "type" at the start.

Fixes: bf9c0538e485 ("ataflop: use a separate gendisk for each media format")
Reported-by: kernel test robot <lkp@...el.com>
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
Reviewed-by: Christoph Hellwig <hch@....de>
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/block/ataflop.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/block/ataflop.c b/drivers/block/ataflop.c
index aed2c2a4f4ea..d601e49f80e0 100644
--- a/drivers/block/ataflop.c
+++ b/drivers/block/ataflop.c
@@ -2001,7 +2001,10 @@ static void ataflop_probe(dev_t dev)
 	int drive = MINOR(dev) & 3;
 	int type  = MINOR(dev) >> 2;
 
-	if (drive >= FD_MAX_UNITS || type > NUM_DISK_MINORS)
+	if (type)
+		type--;
+
+	if (drive >= FD_MAX_UNITS || type >= NUM_DISK_MINORS)
 		return;
 	mutex_lock(&ataflop_probe_lock);
 	if (!unit[drive].disk[type]) {
-- 
2.30.2