RDMA/core: Make sure "ib_port" is valid when access sysfs node

In the Linux kernel, the following vulnerability has been resolved:

RDMA/core: Make sure "ib_port" is valid when access sysfs node

The "ib_port" structure must be set before adding the sysfs kobject,

and reset after removing it, otherwise it may crash when accessing

the sysfs node:

Unable to handle kernel NULL pointer dereference at virtual address 0000000000000050

Mem abort info:

ESR = 0x96000006

Exception class = DABT (current EL), IL = 32 bits

SET = 0, FnV = 0

EA = 0, S1PTW = 0

Data abort info:

ISV = 0, ISS = 0x00000006

CM = 0, WnR = 0

user pgtable: 4k pages, 48-bit VAs, pgdp = 00000000e85f5ba5

[0000000000000050] pgd=0000000848fd9003, pud=000000085b387003, pmd=0000000000000000

Internal error: Oops: 96000006 [#2] PREEMPT SMP

Modules linked in: ib_umad(O) mlx5_ib(O) nfnetlink_cttimeout(E) nfnetlink(E) act_gact(E) cls_flower(E) sch_ingress(E) openvswitch(E) nsh(E) nf_nat_ipv6(E) nf_nat_ipv4(E) nf_conncount(E) nf_nat(E) nf_conntrack(E) nf_defrag_ipv6(E) nf_defrag_ipv4(E) mst_pciconf(O) ipmi_devintf(E) ipmi_msghandler(E) ipmb_dev_int(OE) mlx5_core(O) mlxfw(O) mlxdevm(O) auxiliary(O) ib_uverbs(O) ib_core(O) mlx_compat(O) psample(E) sbsa_gwdt(E) uio_pdrv_genirq(E) uio(E) mlxbf_pmc(OE) mlxbf_gige(OE) mlxbf_tmfifo(OE) gpio_mlxbf2(OE) pwr_mlxbf(OE) mlx_trio(OE) i2c_mlxbf(OE) mlx_bootctl(OE) bluefield_edac(OE) knem(O) ip_tables(E) ipv6(E) crc_ccitt(E) [last unloaded: mst_pci]

Process grep (pid: 3372, stack limit = 0x0000000022055c92)

CPU: 5 PID: 3372 Comm: grep Tainted: G D OE 4.19.161-mlnx.47.gadcd9e3 #1

Hardware name: https://www.mellanox.com BlueField SoC/BlueField SoC, BIOS BlueField:3.9.2-15-ga2403ab Sep 8 2022

pstate: 40000005 (nZcv daif -PAN -UAO)

pc : hw_stat_port_show+0x4c/0x80 [ib_core]

lr : port_attr_show+0x40/0x58 [ib_core]

sp : ffff000029f43b50

x29: ffff000029f43b50 x28: 0000000019375000

x27: ffff8007b821a540 x26: ffff000029f43e30

x25: 0000000000008000 x24: ffff000000eaa958

x23: 0000000000001000 x22: ffff8007a4ce3000

x21: ffff8007baff8000 x20: ffff8007b9066ac0

x19: ffff8007bae97578 x18: 0000000000000000

x17: 0000000000000000 x16: 0000000000000000

x15: 0000000000000000 x14: 0000000000000000

x13: 0000000000000000 x12: 0000000000000000

x11: 0000000000000000 x10: 0000000000000000

x9 : 0000000000000000 x8 : ffff8007a4ce4000

x7 : 0000000000000000 x6 : 000000000000003f

x5 : ffff000000e6a280 x4 : ffff8007a4ce3000

x3 : 0000000000000000 x2 : aaaaaaaaaaaaaaab

x1 : ffff8007b9066a10 x0 : ffff8007baff8000

Call trace:

hw_stat_port_show+0x4c/0x80 [ib_core]

port_attr_show+0x40/0x58 [ib_core]

sysfs_kf_seq_show+0x8c/0x150

kernfs_seq_show+0x44/0x50

seq_read+0x1b4/0x45c

kernfs_fop_read+0x148/0x1d8

__vfs_read+0x58/0x180

vfs_read+0x94/0x154

ksys_read+0x68/0xd8

__arm64_sys_read+0x28/0x34

el0_svc_common+0x88/0x18c

el0_svc_handler+0x78/0x94

el0_svc+0x8/0xe8

Code: f2955562 aa1603e4 aa1503e0 f9405683 (f9402861)