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From: Luis Chamberlain <mcgrof@kernel.org>
To: axboe@kernel.dk, efremov@linux.com, hch@lst.de
Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
	Luis Chamberlain <mcgrof@kernel.org>
Subject: [PATCH 04/14] floppy: fix calling platform_device_unregister() on invalid drives
Date: Fri,  3 Sep 2021 18:35:26 -0700	[thread overview]
Message-ID: <20210904013536.3181237-5-mcgrof@kernel.org> (raw)
In-Reply-To: <20210904013536.3181237-1-mcgrof@kernel.org>

platform_device_unregister() should only be called when
a respective platform_device_register() is called. However
the floppy driver currently allows failures when registring
a drive and a bail out could easily cause an invalid call
to platform_device_unregister() where it was not intended.

Fix this by adding a bool to keep track of when the platform
device was registered for a drive.

This does not fix any known panic / bug. This issue was found
through code inspection while preparing the driver to use the
up and coming support for device_add_disk() error handling.
From what I can tell from code inspection, chances of this
ever happening should be insanely small, perhaps OOM.

Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
---
 drivers/block/floppy.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
index 9538146e520e..3592a6277d0b 100644
--- a/drivers/block/floppy.c
+++ b/drivers/block/floppy.c
@@ -4478,6 +4478,7 @@ static const struct blk_mq_ops floppy_mq_ops = {
 };
 
 static struct platform_device floppy_device[N_DRIVE];
+static bool registered[N_DRIVE];
 
 static bool floppy_available(int drive)
 {
@@ -4693,6 +4694,8 @@ static int __init do_floppy_init(void)
 		if (err)
 			goto out_remove_drives;
 
+		registered[drive] = true;
+
 		device_add_disk(&floppy_device[drive].dev, disks[drive][0],
 				NULL);
 	}
@@ -4703,7 +4706,8 @@ static int __init do_floppy_init(void)
 	while (drive--) {
 		if (floppy_available(drive)) {
 			del_gendisk(disks[drive][0]);
-			platform_device_unregister(&floppy_device[drive]);
+			if (registered[drive])
+				platform_device_unregister(&floppy_device[drive]);
 		}
 	}
 out_release_dma:
@@ -4946,7 +4950,8 @@ static void __exit floppy_module_exit(void)
 				if (disks[drive][i])
 					del_gendisk(disks[drive][i]);
 			}
-			platform_device_unregister(&floppy_device[drive]);
+			if (registered[drive])
+				platform_device_unregister(&floppy_device[drive]);
 		}
 		for (i = 0; i < ARRAY_SIZE(floppy_type); i++) {
 			if (disks[drive][i])
-- 
2.30.2


  parent reply	other threads:[~2021-09-04  1:35 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-04  1:35 [PATCH 00/14] block: 6th batch of add_disk() error handling conversions Luis Chamberlain
2021-09-04  1:35 ` [PATCH 01/14] block/swim3: add error handling support for add_disk() Luis Chamberlain
2021-09-04  1:35 ` [PATCH 02/14] floppy: fix add_disk() assumption on exit due to new developments Luis Chamberlain
2021-09-04  1:35 ` [PATCH 03/14] floppy: use blk_cleanup_disk() Luis Chamberlain
2021-09-04  1:35 ` Luis Chamberlain [this message]
2021-09-04  1:35 ` [PATCH 05/14] floppy: add error handling support for add_disk() Luis Chamberlain
2021-09-04  1:35 ` [PATCH 06/14] amiflop: " Luis Chamberlain
2021-09-04  1:35 ` [PATCH 07/14] swim: simplify using blk_cleanup_disk() on swim_remove() Luis Chamberlain
2021-09-04  1:35 ` [PATCH 08/14] swim: add helper for disk cleanup Luis Chamberlain
2021-09-04  1:35 ` [PATCH 09/14] swim: add a floppy registration bool which triggers del_gendisk() Luis Chamberlain
2021-09-04  1:35 ` [PATCH 10/14] swim: add error handling support for add_disk() Luis Chamberlain
2021-09-04  1:35 ` [PATCH 11/14] block/ataflop: use the blk_cleanup_disk() helper Luis Chamberlain
2021-09-04  1:35 ` [PATCH 12/14] block/ataflop: add registration bool before calling del_gendisk() Luis Chamberlain
2021-09-04  1:35 ` [PATCH 13/14] block/ataflop: provide a helper for cleanup up an atari disk Luis Chamberlain
2021-09-04  1:35 ` [PATCH 14/14] block/ataflop add error handling support for add_disk() Luis Chamberlain

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