Bluetooth: bnep: reject short frames before parsing

Bluetooth: bnep: reject short frames before parsing

A BNEP peer can send a short BNEP SDU. bnep_rx_frame() reads the
packet type byte immediately and, for control packets, reads the control
opcode and setup UUID-size byte before proving that those bytes are
present. bnep_rx_control() also dereferences the control opcode without
rejecting an empty control payload.

Use skb_pull_data() for the fixed fields in bnep_rx_frame() so a NULL
return gates each dereference. Split the control handler so the frame
path can pass an opcode that has already been pulled, and keep the
byte-buffer wrapper for extension control payloads.

For BNEP_SETUP_CONN_REQ, name the UUID-size byte before pulling the
setup payload. struct bnep_setup_conn_req carries destination and source
service UUIDs after that byte, each uuid_size bytes, so the parser now
documents that tuple explicitly instead of leaving the pull length as an
opaque multiplication.

Validation reproduced this kernel report:
KASAN slab-out-of-bounds in bnep_rx_frame.isra.0+0x130c/0x1790
The buggy address belongs to the object at ffff88800c0f7908 which belongs
to the cache kmalloc-8 of size 8
The buggy address is located 0 bytes to the right of allocated 1-byte
region [ffff88800c0f7908, ffff88800c0f7909)
Read of size 1
Call trace:
  dump_stack_lvl+0xb3/0x140 (?:?)
  print_address_description+0x57/0x3a0 (?:?)
  bnep_rx_frame+0x130c/0x1790 (net/bluetooth/bnep/core.c:306)
  print_report+0xb9/0x2b0 (?:?)
  __virt_addr_valid+0x1ba/0x3a0 (?:?)
  srso_alias_return_thunk+0x5/0xfbef5 (?:?)
  kasan_addr_to_slab+0x21/0x60 (?:?)
  kasan_report+0xe0/0x110 (?:?)
  process_one_work+0xfce/0x17e0 (kernel/workqueue.c:3200)
  worker_thread+0x65c/0xe40 (?:?)
  __kthread_parkme+0x184/0x230 (?:?)
  kthread+0x35e/0x470 (?:?)
  _raw_spin_unlock_irq+0x28/0x50 (?:?)
  ret_from_fork+0x586/0x870 (?:?)
  __switch_to+0x74f/0xdc0 (?:?)
  ret_from_fork_asm+0x1a/0x30 (?:?)

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Assisted-by: Codex:gpt-5.5
Signed-off-by: Zhang Cen <rollkingzzc@gmail.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>