[PATCH] nvme: fix NULL pointer dereference

[Tong Zhang]

blk_mq_tag_to_rq can return NULL and this condition must be checked

[  147.861050] BUG: KASAN: null-ptr-deref in nvme_irq+0xfc/0x410
[  147.861326] Write of size 2 at addr 0000000000000122 by task kworker/u4:1/56
[  147.861675]
[  147.861756] CPU: 1 PID: 56 Comm: kworker/u4:1 Not tainted 5.9.0-rc4+ #83
[  147.862657] Workqueue: nvme-wq nvme_scan_work
[  147.862876] Call Trace:
[  147.863002]  <IRQ>
[  147.863112]  dump_stack+0x7d/0xb0
[  147.863280]  kasan_report.cold+0x6a/0x7e
[  147.863478]  ? nvme_irq+0xfc/0x410
[  147.863650]  nvme_irq+0xfc/0x410
[  147.863815]  ? __x64_sys_getrandom+0xb0/0xb0
[  147.864030]  ? nvme_del_cq_end+0x70/0x70
[  147.864229]  __handle_irq_event_percpu+0x69/0x280
[  147.864465]  handle_irq_event_percpu+0x6a/0xe0
[  147.864689]  ? __handle_irq_event_percpu+0x280/0x280
[  147.864939]  ? _raw_spin_lock+0x75/0xd0
[  147.865131]  ? _raw_read_lock_irq+0x30/0x30
[  147.865345]  handle_irq_event+0x57/0x86
[  147.865537]  handle_edge_irq+0xe5/0x2d0
[  147.865732]  asm_call_on_stack+0x12/0x20
[  147.865929]  </IRQ>
[  147.866038]  common_interrupt+0xad/0x110
[  147.866236]  asm_common_interrupt+0x1e/0x40
[  147.866447] RIP: 0010:__asan_load4+0x40/0xa0
[  147.866663] Code: 00 00 ff 48 39 f8 77 56 48 8d 47 03 48 89 c2 83 e2 07 48 83 fa 02 76 2f 48 b9 00 00 00 00 00 fc ff df 48 c1 e8 03 0f b6 04 08 <84>0
[  147.867577] RSP: 0000:ffff8880666e6d48 EFLAGS: 00000a06
[  147.867837] RAX: 0000000000000000 RBX: ffff8880666e6e28 RCX: dffffc0000000000
[  147.868190] RDX: 0000000000000003 RSI: ffffffffb053e44f RDI: ffff8880666e6e30
[  147.868544] RBP: 0000000000000013 R08: ffffffffafb5ee6f R09: fffffbfff64977ad
[  147.868897] R10: ffffffffb24bbd63 R11: fffffbfff64977ac R12: ffffffffb053e44f
[  147.869250] R13: 0000000000000000 R14: ffff8880666d8040 R15: 0000000000000130

Signed-off-by: Tong Zhang <ztong0001 at gmail.com>
---
 drivers/nvme/host/pci.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 899d2f4d7ab6..725d2263a0f5 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -960,6 +960,8 @@ static inline void nvme_handle_cqe(struct nvme_queue *nvmeq, u16 idx)
 	}
 
 	req = blk_mq_tag_to_rq(nvme_queue_tagset(nvmeq), cqe->command_id);
+	if (!req)
+		return;
 	trace_nvme_sq(req, cqe->sq_head, nvmeq->sq_tail);
 	if (!nvme_try_complete_req(req, cqe->status, cqe->result))
 		nvme_pci_complete_rq(req);
-- 
2.25.1