RDMA/hns: bugfix for slab-out-of-bounds when loading hip08 driver

kasan will report a BUG when run command 'insmod hns_roce_hw_v2.ko', the
calltrace is as follows:

==================================================================
BUG: KASAN: slab-out-of-bounds in hns_roce_v2_init_eq_table+0x1324/0x1948
[hns_roce_hw_v2]
Read of size 8 at addr ffff8020e7a10608 by task insmod/256

CPU: 0 PID: 256 Comm: insmod Tainted: G           O      5.2.0-rc4 #1
Hardware name: Huawei D06 /D06, BIOS Hisilicon D06 UEFI RC0
Call trace:
dump_backtrace+0x0/0x1e8
show_stack+0x14/0x20
dump_stack+0xc4/0xfc
print_address_description+0x60/0x270
__kasan_report+0x164/0x1b8
kasan_report+0xc/0x18
__asan_load8+0x84/0xa8
hns_roce_v2_init_eq_table+0x1324/0x1948 [hns_roce_hw_v2]
hns_roce_init+0xf8/0xfe0 [hns_roce]
__hns_roce_hw_v2_init_instance+0x284/0x330 [hns_roce_hw_v2]
hns_roce_hw_v2_init_instance+0xd0/0x1b8 [hns_roce_hw_v2]
hclge_init_roce_client_instance+0x180/0x310 [hclge]
hclge_init_client_instance+0xcc/0x508 [hclge]
hnae3_init_client_instance.part.3+0x3c/0x80 [hnae3]
hnae3_register_client+0x134/0x1a8 [hnae3]
hns_roce_hw_v2_init+0x14/0x10000 [hns_roce_hw_v2]
do_one_initcall+0x9c/0x3e0
do_init_module+0xd4/0x2d8
load_module+0x3284/0x3690
__se_sys_init_module+0x274/0x308
__arm64_sys_init_module+0x40/0x50
el0_svc_handler+0xbc/0x210
el0_svc+0x8/0xc

Allocated by task 256:
__kasan_kmalloc.isra.0+0xd0/0x180
kasan_kmalloc+0xc/0x18
__kmalloc+0x16c/0x328
hns_roce_v2_init_eq_table+0x764/0x1948 [hns_roce_hw_v2]
hns_roce_init+0xf8/0xfe0 [hns_roce]
__hns_roce_hw_v2_init_instance+0x284/0x330 [hns_roce_hw_v2]
hns_roce_hw_v2_init_instance+0xd0/0x1b8 [hns_roce_hw_v2]
hclge_init_roce_client_instance+0x180/0x310 [hclge]
hclge_init_client_instance+0xcc/0x508 [hclge]
hnae3_init_client_instance.part.3+0x3c/0x80 [hnae3]
hnae3_register_client+0x134/0x1a8 [hnae3]
hns_roce_hw_v2_init+0x14/0x10000 [hns_roce_hw_v2]
do_one_initcall+0x9c/0x3e0
do_init_module+0xd4/0x2d8
load_module+0x3284/0x3690
__se_sys_init_module+0x274/0x308
__arm64_sys_init_module+0x40/0x50
el0_svc_handler+0xbc/0x210
el0_svc+0x8/0xc

Freed by task 0:
(stack is not available)

The buggy address belongs to the object at ffff8020e7a10600
which belongs to the cache kmalloc-128 of size 128
The buggy address is located 8 bytes inside of
128-byte region [ffff8020e7a10600, ffff8020e7a10680)
The buggy address belongs to the page:
page:ffff7fe00839e840 refcount:1 mapcount:0 mapping:ffff802340020200 index:0x0
flags: 0x5fffe00000000200(slab)
raw: 5fffe00000000200 dead000000000100 dead000000000200 ffff802340020200
raw: 0000000000000000 0000000081000100 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8020e7a10500: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
ffff8020e7a10580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8020e7a10600: 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^
ffff8020e7a10680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8020e7a10700: 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
Disabling lock debugging due to kernel taint

Fixes: a5073d6054 ("RDMA/hns: Add eq support of hip08")

Signed-off-by: Xi Wang <wangxi11@huawei.com>
Link: https://lore.kernel.org/r/1565343666-73193-7-git-send-email-oulijun@huawei.com
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/hns/hns_roce_hw_v2.c

@@ -5547,7 +5547,8 @@ static int hns_roce_mhop_alloc_eq(struct hns_roce_dev *hr_dev,
 				break;
 		}
 		eq->cur_eqe_ba = eq->buf_dma[0];
-		eq->nxt_eqe_ba = eq->buf_dma[1];
+		if (ba_num > 1)
+			eq->nxt_eqe_ba = eq->buf_dma[1];
 
 	} else if (mhop_num == 2) {
 		/* alloc L1 BT and buf */
@@ -5588,7 +5589,8 @@ static int hns_roce_mhop_alloc_eq(struct hns_roce_dev *hr_dev,
 				break;
 		}
 		eq->cur_eqe_ba = eq->buf_dma[0];
-		eq->nxt_eqe_ba = eq->buf_dma[1];
+		if (ba_num > 1)
+			eq->nxt_eqe_ba = eq->buf_dma[1];
 	}
 
 	eq->l0_last_num = i + 1;