[PATCH] nvme: fix heap-use-after-free and oops in bio_endio for nv= multipath

[Lei Yin]

When blk_queue_split works in nvme_ns_head_submit_bio, input bio will be
splited to two bios. If parent bio is completed first, and the bi_disk
in parent bio is kfreed by nvme_free_ns, child will access this freed
bi_disk in bio_endio. This will trigger heap-use-after-free or null
pointer oops.

The following is kasan report:

BUG: KASAN: use-after-free in bio_endio+0x477/0x500
Read of size 8 at addr ffff888106f2e3a8 by task kworker/1:1H/241

CPU: 1 PID: 241 Comm: kworker/1:1H Kdump: loaded Tainted: G           O
      5.10.167 #1
Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
Workqueue: kblockd nvme_requeue_work [nvme_core]
Call Trace:
 dump_stack+0x92/0xc4
 ? bio_endio+0x477/0x500
 print_address_description.constprop.7+0x1e/0x230
 ? record_print_text.cold.40+0x11/0x11
 ? _raw_spin_trylock_bh+0x120/0x120
 ? blk_throtl_bio+0x225/0x3050
 ? bio_endio+0x477/0x500
 ? bio_endio+0x477/0x500
 kasan_report.cold.9+0x37/0x7c
 ? bio_endio+0x477/0x500
 bio_endio+0x477/0x500
 nvme_ns_head_submit_bio+0x950/0x1130 [nvme_core]
 ? nvme_find_path+0x7f0/0x7f0 [nvme_core]
 ? __kasan_slab_free+0x11a/0x150
 ? bio_endio+0x213/0x500
 submit_bio_noacct+0x2a4/0xd10
 ? _dev_info+0xcd/0xff
 ? _dev_notice+0xff/0xff
 ? blk_queue_enter+0x6c0/0x6c0
 ? _raw_spin_lock_irq+0x81/0xd5
 ? _raw_spin_lock+0xd0/0xd0
 nvme_requeue_work+0x144/0x18c [nvme_core]
 process_one_work+0x878/0x13e0
 worker_thread+0x87/0xf70
 ? __kthread_parkme+0x8f/0x100
 ? process_one_work+0x13e0/0x13e0
 kthread+0x30f/0x3d0
 ? kthread_parkme+0x80/0x80
 ret_from_fork+0x1f/0x30

Allocated by task 52:
 kasan_save_stack+0x19/0x40
 __kasan_kmalloc.constprop.11+0xc8/0xd0
 __alloc_disk_node+0x5c/0x320
 nvme_alloc_ns+0x6e9/0x1520 [nvme_core]
 nvme_validate_or_alloc_ns+0x17c/0x370 [nvme_core]
 nvme_scan_work+0x2d4/0x4d0 [nvme_core]
 process_one_work+0x878/0x13e0
 worker_thread+0x87/0xf70
 kthread+0x30f/0x3d0
 ret_from_fork+0x1f/0x30

Freed by task 54:
 kasan_save_stack+0x19/0x40
 kasan_set_track+0x1c/0x30
 kasan_set_free_info+0x1b/0x30
 __kasan_slab_free+0x108/0x150
 kfree+0xa7/0x300
 device_release+0x98/0x210
 kobject_release+0x109/0x3a0
 nvme_free_ns+0x15e/0x1f7 [nvme_core]
 nvme_remove_namespaces+0x22f/0x390 [nvme_core]
 nvme_do_delete_ctrl+0xac/0x106 [nvme_core]
 process_one_work+0x878/0x13e0
 worker_thread+0x87/0xf70
 kthread+0x30f/0x3d0
 ret_from_fork+0x1f/0x30

Signed-off-by: Lei Yin <yinlei2@xxxxxxxxxx>
---
 drivers/nvme/host/nvme.h | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index c3e4d9b6f9c0..b441c5ce4157 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -749,8 +749,17 @@ static inline void nvme_trace_bio_complete(struct requ=
est *req,
 {
 	struct nvme_ns *ns =3D req->q->queuedata;
=20
-	if ((req->cmd_flags & REQ_NVME_MPATH) && req->bio)
+	if ((req->cmd_flags & REQ_NVME_MPATH) && req->bio) {
 		trace_block_bio_complete(ns->head->disk->queue, req->bio);
+
+		/* Point bio->bi_disk to head disk.
+		 * This bio maybe as other bio's parent in bio chain. If this bi_disk
+		 * is kfreed by nvme_free_ns, other bio may get this bio by __bio_chain_=
endio
+		 * in bio_endio, and access this bi_disk. This will trigger heap-use-aft=
er-free
+		 * or null pointer oops.
+		 */
+		req->bio->bi_disk =3D ns->head->disk;
+	}
 }
=20
 extern struct device_attribute dev_attr_ana_grpid;
--=20
2.39.1