scsi: snic: Fix possible UAF in snic_tgt_create()

Smatch reports a warning as follows:

drivers/scsi/snic/snic_disc.c:307 snic_tgt_create() warn:
  '&tgt->list' not removed from list

If device_add() fails in snic_tgt_create(), tgt will be freed, but
tgt->list will not be removed from snic->disc.tgt_list, then list traversal
may cause UAF.

Remove from snic->disc.tgt_list before free().

Fixes: c8806b6c9e ("snic: driver for Cisco SCSI HBA")
Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
Link: https://lore.kernel.org/r/20221117035100.2944812-1-cuigaosheng1@huawei.com
Acked-by: Narsimhulu Musini <nmusini@cisco.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/snic/snic_disc.c

@@ -304,6 +304,9 @@ snic_tgt_create(struct snic *snic, struct snic_tgt_id *tgtid)
 			      ret);
 
 		put_device(&snic->shost->shost_gendev);
+		spin_lock_irqsave(snic->shost->host_lock, flags);
+		list_del(&tgt->list);
+		spin_unlock_irqrestore(snic->shost->host_lock, flags);
 		kfree(tgt);
 		tgt = NULL;