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authorBart Van Assche <bart.vanassche@wdc.com>2017-08-17 13:12:45 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-09-27 14:39:21 +0200
commitcb1441bca9bf23c6cf715d16843f71f8e516993d (patch)
tree980de561c4cae8c51d3e8c91838c589df5ddb790 /drivers/block
parent2cee78081b97366c42bb6349be2a57f89c36df5a (diff)
skd: Avoid that module unloading triggers a use-after-free
commit 7277cc67b3916eed47558c64f9c9c0de00a35cda upstream. Since put_disk() triggers a disk_release() call and since that last function calls blk_put_queue() if disk->queue != NULL, clear the disk->queue pointer before calling put_disk(). This avoids that unloading the skd kernel module triggers the following use-after-free: WARNING: CPU: 8 PID: 297 at lib/refcount.c:128 refcount_sub_and_test+0x70/0x80 refcount_t: underflow; use-after-free. CPU: 8 PID: 297 Comm: kworker/8:1 Not tainted 4.11.10-300.fc26.x86_64 #1 Workqueue: events work_for_cpu_fn Call Trace: dump_stack+0x63/0x84 __warn+0xcb/0xf0 warn_slowpath_fmt+0x5a/0x80 refcount_sub_and_test+0x70/0x80 refcount_dec_and_test+0x11/0x20 kobject_put+0x1f/0x50 blk_put_queue+0x15/0x20 disk_release+0xae/0xf0 device_release+0x32/0x90 kobject_release+0x67/0x170 kobject_put+0x2b/0x50 put_disk+0x17/0x20 skd_destruct+0x5c/0x890 [skd] skd_pci_probe+0x124d/0x13a0 [skd] local_pci_probe+0x42/0xa0 work_for_cpu_fn+0x14/0x20 process_one_work+0x19e/0x470 worker_thread+0x1dc/0x4a0 kthread+0x125/0x140 ret_from_fork+0x25/0x30 Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Hannes Reinecke <hare@suse.de> Cc: Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/block')
-rw-r--r--drivers/block/skd_main.c17
1 files changed, 9 insertions, 8 deletions
diff --git a/drivers/block/skd_main.c b/drivers/block/skd_main.c
index 3822eae102db..54ffd27b2620 100644
--- a/drivers/block/skd_main.c
+++ b/drivers/block/skd_main.c
@@ -4622,15 +4622,16 @@ static void skd_free_disk(struct skd_device *skdev)
{
struct gendisk *disk = skdev->disk;
- if (disk != NULL) {
- struct request_queue *q = disk->queue;
-
- if (disk->flags & GENHD_FL_UP)
- del_gendisk(disk);
- if (q)
- blk_cleanup_queue(q);
- put_disk(disk);
+ if (disk && (disk->flags & GENHD_FL_UP))
+ del_gendisk(disk);
+
+ if (skdev->queue) {
+ blk_cleanup_queue(skdev->queue);
+ skdev->queue = NULL;
+ disk->queue = NULL;
}
+
+ put_disk(disk);
skdev->disk = NULL;
}