linux-kernel - Re: [PATCH] nvme: fix use-after-free during booting

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Date:   Wed, 23 Sep 2020 07:57:25 +0200
From:   Christoph Hellwig <hch@....de>
To:     Tong Zhang <ztong0001@...il.com>
Cc:     Christoph Hellwig <hch@....de>, Keith Busch <kbusch@...nel.org>,
        Jens Axboe <axboe@...com>, Sagi Grimberg <sagi@...mberg.me>,
        linux-nvme@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] nvme: fix use-after-free during booting

I suspect the patch below might be better.  Can you send me a full dmesg
with this one applied?  Preferably on top of Jens' for-next branch?


diff --git a/block/genhd.c b/block/genhd.c
index 9d060e79eb31d8..ef2784c69d59ee 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -832,7 +832,9 @@ static void __device_add_disk(struct device *parent, struct gendisk *disk,
 	 * Take an extra ref on queue which will be put on disk_release()
 	 * so that it sticks around as long as @disk is there.
 	 */
-	WARN_ON_ONCE(!blk_get_queue(disk->queue));
+	WARN_ON_ONCE(blk_queue_dying(disk->queue));
+	__blk_get_queue(disk->queue);
+	disk->flags |= GENHD_FL_QUEUE_REF;
 
 	disk_add_events(disk);
 	blk_integrity_add(disk);
@@ -1564,7 +1566,7 @@ static void disk_release(struct device *dev)
 	kfree(disk->random);
 	disk_replace_part_tbl(disk, NULL);
 	hd_free_part(&disk->part0);
-	if (disk->queue)
+	if (disk->flags & GENHD_FL_QUEUE_REF)
 		blk_put_queue(disk->queue);
 	kfree(disk);
 }
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 1c97cf84f011a7..822a619924e3b5 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -133,6 +133,7 @@ struct hd_struct {
 #define GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE	0x0100
 #define GENHD_FL_NO_PART_SCAN			0x0200
 #define GENHD_FL_HIDDEN				0x0400
+#define GENHD_FL_QUEUE_REF			0x0800
 
 enum {
 	DISK_EVENT_MEDIA_CHANGE			= 1 << 0, /* media changed */