CVE-2024-47687: vdpa/mlx5: Fix invalid mr resource destroy
In the Linux kernel, the following vulnerability has been resolved:

vdpa/mlx5: Fix invalid mr resource destroy

Certain error paths from mlx5_vdpa_dev_add() can end up releasing mr
resources which never got initialized in the first place.

This patch adds the missing check in mlx5_vdpa_destroy_mr_resources()
to block releasing non-initialized mr resources.

Reference trace:

  mlx5_core 0000:08:00.2: mlx5_vdpa_dev_add:3274:(pid 2700) warning: No mac address provisioned?
  BUG: kernel NULL pointer dereference, address: 0000000000000000
  #PF: supervisor read access in kernel mode
  #PF: error_code(0x0000) - not-present page
  PGD 140216067 P4D 0
  Oops: 0000 [#1] PREEMPT SMP NOPTI
  CPU: 8 PID: 2700 Comm: vdpa Kdump: loaded Not tainted 5.14.0-496.el9.x86_64 #1
  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
  RIP: 0010:vhost_iotlb_del_range+0xf/0xe0 [vhost_iotlb]
  Code: [...]
  RSP: 0018:ff1c823ac23077f0 EFLAGS: 00010246
  RAX: ffffffffc1a21a60 RBX: ffffffff899567a0 RCX: 0000000000000000
  RDX: ffffffffffffffff RSI: 0000000000000000 RDI: 0000000000000000
  RBP: ff1bda1f7c21e800 R08: 0000000000000000 R09: ff1c823ac2307670
  R10: ff1c823ac2307668 R11: ffffffff8a9e7b68 R12: 0000000000000000
  R13: 0000000000000000 R14: ff1bda1f43e341a0 R15: 00000000ffffffea
  FS:  00007f56eba7c740(0000) GS:ff1bda269f800000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 0000000000000000 CR3: 0000000104d90001 CR4: 0000000000771ef0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  PKRU: 55555554
  Call Trace:

   ? show_trace_log_lvl+0x1c4/0x2df
   ? show_trace_log_lvl+0x1c4/0x2df
   ? mlx5_vdpa_free+0x3d/0x150 [mlx5_vdpa]
   ? __die_body.cold+0x8/0xd
   ? page_fault_oops+0x134/0x170
   ? __irq_work_queue_local+0x2b/0xc0
   ? irq_work_queue+0x2c/0x50
   ? exc_page_fault+0x62/0x150
   ? asm_exc_page_fault+0x22/0x30
   ? __pfx_mlx5_vdpa_free+0x10/0x10 [mlx5_vdpa]
   ? vhost_iotlb_del_range+0xf/0xe0 [vhost_iotlb]
   mlx5_vdpa_free+0x3d/0x150 [mlx5_vdpa]
   vdpa_release_dev+0x1e/0x50 [vdpa]
   device_release+0x31/0x90
   kobject_cleanup+0x37/0x130
   mlx5_vdpa_dev_add+0x2d2/0x7a0 [mlx5_vdpa]
   vdpa_nl_cmd_dev_add_set_doit+0x277/0x4c0 [vdpa]
   genl_family_rcv_msg_doit+0xd9/0x130
   genl_family_rcv_msg+0x14d/0x220
   ? __pfx_vdpa_nl_cmd_dev_add_set_doit+0x10/0x10 [vdpa]
   ? _copy_to_user+0x1a/0x30
   ? move_addr_to_user+0x4b/0xe0
   genl_rcv_msg+0x47/0xa0
   ? __import_iovec+0x46/0x150
   ? __pfx_genl_rcv_msg+0x10/0x10
   netlink_rcv_skb+0x54/0x100
   genl_rcv+0x24/0x40
   netlink_unicast+0x245/0x370
   netlink_sendmsg+0x206/0x440
   __sys_sendto+0x1dc/0x1f0
   ? do_read_fault+0x10c/0x1d0
   ? do_pte_missing+0x10d/0x190
   __x64_sys_sendto+0x20/0x30
   do_syscall_64+0x5c/0xf0
   ? __count_memcg_events+0x4f/0xb0
   ? mm_account_fault+0x6c/0x100
   ? handle_mm_fault+0x116/0x270
   ? do_user_addr_fault+0x1d6/0x6a0
   ? do_syscall_64+0x6b/0xf0
   ? clear_bhb_loop+0x25/0x80
   ? clear_bhb_loop+0x25/0x80
   ? clear_bhb_loop+0x25/0x80
   ? clear_bhb_loop+0x25/0x80
   ? clear_bhb_loop+0x25/0x80
   entry_SYSCALL_64_after_hwframe+0x78/0x80
CVSS v3.1: 5.5