RDMA/sa_query: Use strscpy_pad instead of memcpy to copy a string

RDMA/sa_query: Use strscpy_pad instead of memcpy to copy a string

When copying the device name, the length of the data memcpy copied exceeds
the length of the source buffer, which cause the KASAN issue below.  Use
strscpy_pad() instead.

 BUG: KASAN: slab-out-of-bounds in ib_nl_set_path_rec_attrs+0x136/0x320 [ib_core]
 Read of size 64 at addr ffff88811a10f5e0 by task rping/140263
 CPU: 3 PID: 140263 Comm: rping Not tainted 5.15.0-rc1+ #1
 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
 Call Trace:
  dump_stack_lvl+0x57/0x7d
  print_address_description.constprop.0+0x1d/0xa0
  kasan_report+0xcb/0x110
  kasan_check_range+0x13d/0x180
  memcpy+0x20/0x60
  ib_nl_set_path_rec_attrs+0x136/0x320 [ib_core]
  ib_nl_make_request+0x1c6/0x380 [ib_core]
  send_mad+0x20a/0x220 [ib_core]
  ib_sa_path_rec_get+0x3e3/0x800 [ib_core]
  cma_query_ib_route+0x29b/0x390 [rdma_cm]
  rdma_resolve_route+0x308/0x3e0 [rdma_cm]
  ucma_resolve_route+0xe1/0x150 [rdma_ucm]
  ucma_write+0x17b/0x1f0 [rdma_ucm]
  vfs_write+0x142/0x4d0
  ksys_write+0x133/0x160
  do_syscall_64+0x43/0x90
  entry_SYSCALL_64_after_hwframe+0x44/0xae
 RIP: 0033:0x7f26499aa90f
 Code: 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 29 fd ff ff 48 8b 54 24 18 48 8b 74 24 10 41 89 c0 8b 7c 24 08 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 31 44 89 c7 48 89 44 24 08 e8 5c fd ff ff 48
 RSP: 002b:00007f26495f2dc0 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
 RAX: ffffffffffffffda RBX: 00000000000007d0 RCX: 00007f26499aa90f
 RDX: 0000000000000010 RSI: 00007f26495f2e00 RDI: 0000000000000003
 RBP: 00005632a8315440 R08: 0000000000000000 R09: 0000000000000001
 R10: 0000000000000000 R11: 0000000000000293 R12: 00007f26495f2e00
 R13: 00005632a83154e0 R14: 00005632a8315440 R15: 00005632a830a810

 Allocated by task 131419:
  kasan_save_stack+0x1b/0x40
  __kasan_kmalloc+0x7c/0x90
  proc_self_get_link+0x8b/0x100
  pick_link+0x4f1/0x5c0
  step_into+0x2eb/0x3d0
  walk_component+0xc8/0x2c0
  link_path_walk+0x3b8/0x580
  path_openat+0x101/0x230
  do_filp_open+0x12e/0x240
  do_sys_openat2+0x115/0x280
  __x64_sys_openat+0xce/0x140
  do_syscall_64+0x43/0x90
  entry_SYSCALL_64_after_hwframe+0x44/0xae

Fixes: 2ca546b92a02 ("IB/sa: Route SA pathrecord query through netlink")
Link: https://lore.kernel.org/r/72ede0f6dab61f7f23df9ac7a70666e07ef314b0.1635055496.git.leonro@nvidia.com
Signed-off-by: Mark Zhang <markzhang@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>