CVE-2025-21675 net/mlx5: Clear port select structure when fail to create
In the Linux kernel, the following vulnerability has been resolved:

net/mlx5: Clear port select structure when fail to create

Clear the port select structure on error so no stale values left after
definers are destroyed. That's because the mlx5_lag_destroy_definers()
always try to destroy all lag definers in the tt_map, so in the flow
below lag definers get double-destroyed and cause kernel crash:

  mlx5_lag_port_sel_create()
    mlx5_lag_create_definers()
      mlx5_lag_create_definer()     <- Failed on tt 1
        mlx5_lag_destroy_definers() <- definers[tt=0] gets destroyed
  mlx5_lag_port_sel_create()
    mlx5_lag_create_definers()
      mlx5_lag_create_definer()     <- Failed on tt 0
        mlx5_lag_destroy_definers() <- definers[tt=0] gets double-destroyed

 Unable to handle kernel NULL pointer dereference at virtual address 0000000000000008
 Mem abort info:
   ESR = 0x0000000096000005
   EC = 0x25: DABT (current EL), IL = 32 bits
   SET = 0, FnV = 0
   EA = 0, S1PTW = 0
   FSC = 0x05: level 1 translation fault
 Data abort info:
   ISV = 0, ISS = 0x00000005, ISS2 = 0x00000000
   CM = 0, WnR = 0, TnD = 0, TagAccess = 0
   GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
 user pgtable: 64k pages, 48-bit VAs, pgdp=0000000112ce2e00
 [0000000000000008] pgd=0000000000000000, p4d=0000000000000000, pud=0000000000000000
 Internal error: Oops: 0000000096000005 [#1] PREEMPT SMP
 Modules linked in: iptable_raw bonding ip_gre ip6_gre gre ip6_tunnel tunnel6 geneve ip6_udp_tunnel udp_tunnel ipip tunnel4 ip_tunnel rdma_ucm(OE) rdma_cm(OE) iw_cm(OE) ib_ipoib(OE) ib_cm(OE) ib_umad(OE) mlx5_ib(OE) ib_uverbs(OE) mlx5_fwctl(OE) fwctl(OE) mlx5_core(OE) mlxdevm(OE) ib_core(OE) mlxfw(OE) memtrack(OE) mlx_compat(OE) openvswitch nsh nf_conncount psample xt_conntrack xt_MASQUERADE nf_conntrack_netlink nfnetlink xfrm_user xfrm_algo xt_addrtype iptable_filter iptable_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 br_netfilter bridge stp llc netconsole overlay efi_pstore sch_fq_codel zram ip_tables crct10dif_ce qemu_fw_cfg fuse ipv6 crc_ccitt [last unloaded: mlx_compat(OE)]
  CPU: 3 UID: 0 PID: 217 Comm: kworker/u53:2 Tainted: G           OE      6.11.0+ #2
  Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE
  Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015
  Workqueue: mlx5_lag mlx5_do_bond_work [mlx5_core]
  pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
  pc : mlx5_del_flow_rules+0x24/0x2c0 [mlx5_core]
  lr : mlx5_lag_destroy_definer+0x54/0x100 [mlx5_core]
  sp : ffff800085fafb00
  x29: ffff800085fafb00 x28: ffff0000da0c8000 x27: 0000000000000000
  x26: ffff0000da0c8000 x25: ffff0000da0c8000 x24: ffff0000da0c8000
  x23: ffff0000c31f81a0 x22: 0400000000000000 x21: ffff0000da0c8000
  x20: 0000000000000000 x19: 0000000000000001 x18: 0000000000000000
  x17: 0000000000000000 x16: 0000000000000000 x15: 0000ffff8b0c9350
  x14: 0000000000000000 x13: ffff800081390d18 x12: ffff800081dc3cc0
  x11: 0000000000000001 x10: 0000000000000b10 x9 : ffff80007ab7304c
  x8 : ffff0000d00711f0 x7 : 0000000000000004 x6 : 0000000000000190
  x5 : ffff00027edb3010 x4 : 0000000000000000 x3 : 0000000000000000
  x2 : ffff0000d39b8000 x1 : ffff0000d39b8000 x0 : 0400000000000000
  Call trace:
   mlx5_del_flow_rules+0x24/0x2c0 [mlx5_core]
   mlx5_lag_destroy_definer+0x54/0x100 [mlx5_core]
   mlx5_lag_destroy_definers+0xa0/0x108 [mlx5_core]
   mlx5_lag_port_sel_create+0x2d4/0x6f8 [mlx5_core]
   mlx5_activate_lag+0x60c/0x6f8 [mlx5_core]
   mlx5_do_bond_work+0x284/0x5c8 [mlx5_core]
   process_one_work+0x170/0x3e0
   worker_thread+0x2d8/0x3e0
   kthread+0x11c/0x128
   ret_from_fork+0x10/0x20
  Code: a9025bf5 aa0003f6 a90363f7 f90023f9 (f9400400)
  ---[ end trace 0000000000000000 ]---
CVSS v3.1 score: 5.5