disk_release drops the reference on the request_queue if disk->queue
is set. But many drivers set the pointer early, which means they
have to clear it before calling put_disk during a probe failure,
which is often forgotten. Even worse for drivers that refcount their
per-disk structure like nvme the path for a real teardown vs probe
failure can be shared. Fix all this by setting a gendisk flag only
when add_disk has acquired a request_queue reference, and only drop
the reference when the flag was set. Also make sure add_disk always
grabs a reference, even if the queue is marked dying, as we expect
the reference.
This patch fixes a potential use after free during nvme probe failure.
The fact that nvme can call add_disk on a dying queue is another bug
in the nvme code that we'll fix separatel.
Reported-by: Tong Zhang <ztong0001@xxxxxxxxx>
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
block/genhd.c | 6 ++++--
include/linux/genhd.h | 1 +
2 files changed, 5 insertions(+), 2 deletions(-)
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 */
--
2.28.0
