)]}'
{
  "commit": "518aa9505fa10ea5662349e5d2efd8c9e32a820b",
  "tree": "dbf6d0121e59cd2502dea3fcd3971a4302275c5c",
  "parents": [
    "352a59dc1f4a41314b6f827c17e16af7ca88271a"
  ],
  "author": {
    "name": "Cen Zhang",
    "email": "zzzccc427@gmail.com",
    "time": "Wed Jun 24 00:12:59 2026 +0800"
  },
  "committer": {
    "name": "Luiz Augusto von Dentz",
    "email": "luiz.von.dentz@intel.com",
    "time": "Mon Jul 06 10:46:57 2026 -0400"
  },
  "message": "Bluetooth: 6lowpan: hold L2CAP conn across debugfs control\n\nget_l2cap_conn() looks up an LE hci_conn under hdev protection, but\nthen drops that protection before reading hcon-\u003el2cap_data and before\nlowpan_control_write() later dereferences conn-\u003ehcon.  A disconnect or\ndevice close can tear down the same L2CAP connection in that window.\n\nThe buggy scenario involves two paths, with each column showing the order\nwithin that path:\n\n6LoWPAN control write:              HCI disconnect/device close:\n  1. get_l2cap_conn() finds hcon      1. hci_disconn_cfm() dispatches\n     and hcon-\u003el2cap_data.               the L2CAP disconnect callback.\n  2. get_l2cap_conn() drops hdev      2. l2cap_conn_del() clears\n     protection and returns conn.        hcon-\u003el2cap_data and drops the\n                                         L2CAP connection reference.\n  3. lowpan_control_write() reads     3. hci_conn_del() removes and drops\n     conn-\u003ehcon.                         the HCI connection.\n\nTake a reference to the L2CAP connection with\nl2cap_conn_hold_unless_zero() while hdev is still locked, and drop that\nreference after the debugfs command\u0027s last use of conn.  This mirrors the\nexisting L2CAP ACL receive-side handoff and keeps the connection\ndereferenceable after leaving hdev protection.  Export the existing helper\nso the bluetooth_6lowpan module can use the same lifetime primitive.\n\nValidation reproduced this kernel report:\nBUG: KASAN: slab-use-after-free in lowpan_control_write+0x374/0x520\nThe buggy address belongs to the object at ffff888111b9d000 which belongs\nto the cache kmalloc-1k of size 1024\nThe buggy address is located 0 bytes inside of freed 1024-byte region\n[ffff888111b9d000, ffff888111b9d400)\nRead of size 8\nCall trace:\n  dump_stack_lvl+0x66/0xa0\n  print_report+0xce/0x5f0\n  lowpan_control_write+0x374/0x520 (net/bluetooth/6lowpan.c:1131)\n  srso_alias_return_thunk+0x5/0xfbef5\n  __virt_addr_valid+0x19f/0x330\n  kasan_report+0xe0/0x110\n  __debugfs_file_get+0xf7/0x400\n  full_proxy_write+0x9e/0xd0\n  vfs_write+0x1b0/0x810\n  ksys_write+0xd2/0x170\n  dnotify_flush+0x32/0x220\n  do_syscall_64+0x115/0x6a0 (arch/x86/entry/syscall_64.c:87)\n  entry_SYSCALL_64_after_hwframe+0x77/0x7f\nAllocated by task stack:\n  kasan_save_stack+0x33/0x60\n  kasan_save_track+0x17/0x60\n  __kasan_kmalloc+0xaa/0xb0\n  l2cap_conn_add+0x45/0x520\n  l2cap_chan_connect+0xac6/0xd90\n  l2cap_sock_connect+0x216/0x350\n  __sys_connect+0x101/0x130\n  __x64_sys_connect+0x40/0x50\n  do_syscall_64+0x115/0x6a0 (arch/x86/entry/syscall_64.c:87)\n  entry_SYSCALL_64_after_hwframe+0x77/0x7f\nFreed by task stack:\n  kasan_save_stack+0x33/0x60\n  kasan_save_track+0x17/0x60\n  kasan_save_free_info+0x3b/0x60\n  __kasan_slab_free+0x5f/0x80\n  kfree+0x313/0x590\n  hci_conn_hash_flush+0xc0/0x140\n  hci_dev_close_sync+0x41a/0xb00\n  hci_dev_close+0x12f/0x160\n  hci_sock_ioctl+0x157/0x570\n  sock_do_ioctl+0xf7/0x210\n  sock_ioctl+0x32f/0x490\n  __x64_sys_ioctl+0xc7/0x110\n  do_syscall_64+0x115/0x6a0 (arch/x86/entry/syscall_64.c:87)\n  entry_SYSCALL_64_after_hwframe+0x77/0x7f\n  kasan_record_aux_stack+0xa7/0xc0\n  insert_work+0x32/0x100\n  __queue_work+0x262/0xa60\n  queue_work_on+0xad/0xb0\n  l2cap_connect_cfm+0x4ef/0x670\n  hci_le_remote_feat_complete_evt+0x247/0x430\n  hci_event_packet+0x360/0x6f0\n  hci_rx_work+0x2ae/0x7a0\n  process_one_work+0x4fd/0xbc0\n  worker_thread+0x2d8/0x570\n  kthread+0x1ad/0x1f0\n  ret_from_fork+0x3c9/0x540\n  ret_from_fork_asm+0x1a/0x30\n\nFixes: 6b8d4a6a0314 (\"Bluetooth: 6LoWPAN: Use connected oriented channel instead of fixed one\")\nAssisted-by: Codex:gpt-5.5\nSigned-off-by: Cen Zhang \u003czzzccc427@gmail.com\u003e\nSigned-off-by: Luiz Augusto von Dentz \u003cluiz.von.dentz@intel.com\u003e\n",
  "tree_diff": [
    {
      "type": "modify",
      "old_id": "c4b0a4048be2267aafdfdb43502b9c99d55455d0",
      "old_mode": 33188,
      "old_path": "net/bluetooth/6lowpan.c",
      "new_id": "e7be18a3af3304a88f45e750f97db0775ffd4286",
      "new_mode": 33188,
      "new_path": "net/bluetooth/6lowpan.c"
    },
    {
      "type": "modify",
      "old_id": "a1d249f42be781e2ac827d0cfc3cab0ec366bb77",
      "old_mode": 33188,
      "old_path": "net/bluetooth/l2cap_core.c",
      "new_id": "4ee3b9e30c65b294172ee5be8af74ce653aecc34",
      "new_mode": 33188,
      "new_path": "net/bluetooth/l2cap_core.c"
    }
  ]
}