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A valid SMP Identity Address Information message can update an existing IRK while MGMT Load IRKs replaces the identity resolving key list. l2cap_recv_acldata() drops hdev->lock before SMP processing, so the connection and channel locks do not exclude load_irks(). One possible ordering is: SMP receive worker Management / RCU hci_add_irk() hci_find_irk_by_addr() rcu_read_lock() find matching IRK rcu_read_unlock() load_irks() hci_dev_lock() hci_smp_irks_clear() list_del_rcu() kfree_rcu() hci_dev_unlock() RCU grace period ends IRK is freed memcpy(irk->val, val, 16) bacpy(&irk->rpa, rpa) The receive worker then writes into freed memory. KASAN reported a 16-byte write in hci_add_irk(), 45 bytes into a freed smp_irk allocation. Keep an outer RCU read-side critical section in hci_add_irk() across the lookup and both copies. Drop it before the GFP_KERNEL allocation and reacquire it before publishing a new node. Reclamation must then wait until the stores finish. This also avoids acquiring hdev->lock under the L2CAP locks, which would invert the existing lock order. The change has not been runtime-tested. KASAN report as below: ================================================================== BUG: KASAN: slab-use-after-free in hci_add_irk+0x77/0x2a0 Write of size 16 at addr ffff88810bbdcc2d by task kworker/u17:0/526 Workqueue: hci0 hci_rx_work Call Trace: dump_stack_lvl+0x93/0xd0 print_report+0xce/0x630 ? hci_add_irk+0x77/0x2a0 ? srso_alias_return_thunk+0x5/0xfbef5 ? __virt_addr_valid+0x20d/0x410 ? hci_add_irk+0x77/0x2a0 kasan_report+0xe0/0x110 ? hci_add_irk+0x77/0x2a0 kasan_check_range+0x105/0x1b0 __asan_memcpy+0x3c/0x60 hci_add_irk+0x77/0x2a0 smp_recv_cb+0x594d/0x8e40 ? __pfx_smp_recv_cb+0x10/0x10 ? __pfx___might_resched+0x10/0x10 ? srso_alias_return_thunk+0x5/0xfbef5 ? stack_depot_save_flags+0x29/0x9a0 ? __mutex_lock+0x182c/0x2590 ? kasan_save_stack+0x42/0x60 ? l2cap_recv_frame+0x9ef/0x8830 ? __kasan_slab_free+0x5f/0x80 ? kmem_cache_free+0x242/0x580 ? srso_alias_return_thunk+0x5/0xfbef5 ? find_held_lock+0x2b/0x80 ? l2cap_recv_frame+0xaef/0x8830 ? __pfx___mutex_lock+0x10/0x10 ? __lock_acquire+0x466/0x2260 ? __pfx_l2cap_chan_hold_unless_zero+0x10/0x10 ? l2cap_recv_frame+0x13cc/0x8830 ? __pfx_smp_recv_cb+0x10/0x10 l2cap_recv_frame+0x13cc/0x8830 ? srso_alias_return_thunk+0x5/0xfbef5 ? srso_alias_return_thunk+0x5/0xfbef5 ? __mutex_lock+0x182c/0x2590 ? __pfx_l2cap_recv_frame+0x10/0x10 ? srso_alias_return_thunk+0x5/0xfbef5 ? find_held_lock+0x2b/0x80 ? l2cap_recv_acldata+0x1eb/0x10e0 ? __pfx___mutex_lock+0x10/0x10 ? srso_alias_return_thunk+0x5/0xfbef5 ? __mutex_unlock_slowpath+0x147/0x920 ? __pfx_l2cap_conn_hold_unless_zero+0x10/0x10 ? __pfx_hci_conn_enter_active_mode+0x10/0x10 ? l2cap_recv_acldata+0x13d/0x10e0 ? srso_alias_return_thunk+0x5/0xfbef5 l2cap_recv_acldata+0xe9f/0x10e0 ? srso_alias_return_thunk+0x5/0xfbef5 hci_rx_work+0x5a6/0xf00 ? srso_alias_return_thunk+0x5/0xfbef5 process_one_work+0x908/0x19c0 ? __pfx_process_one_work+0x10/0x10 ? srso_alias_return_thunk+0x5/0xfbef5 ? lock_is_held_type+0x8f/0x100 ? srso_alias_return_thunk+0x5/0xfbef5 worker_thread+0x65c/0xe40 ? __pfx_worker_thread+0x10/0x10 kthread+0x34f/0x460 ? srso_alias_return_thunk+0x5/0xfbef5 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x659/0x940 ? __pfx_ret_from_fork+0x10/0x10 ? srso_alias_return_thunk+0x5/0xfbef5 ? __switch_to+0x74f/0xf80 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1a/0x30 Allocated by task 520: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 __kasan_kmalloc+0xaa/0xb0 __kmalloc_cache_noprof+0x251/0x610 hci_add_irk+0x131/0x2a0 load_irks+0x5fb/0x8c0 hci_sock_sendmsg+0x128b/0x22e0 sock_write_iter+0x4c0/0x550 do_iter_readv_writev+0x59c/0x860 vfs_writev+0x30e/0xc10 do_writev+0x241/0x2f0 do_syscall_64+0x115/0x6a0 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 0: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 kasan_save_free_info+0x3b/0x60 __kasan_slab_free+0x5f/0x80 __rcu_free_sheaf_prepare+0x65/0x2a0 rcu_free_sheaf+0x1f/0xe0 rcu_core+0x661/0x1d10 handle_softirqs+0x201/0x930 __irq_exit_rcu+0x110/0x1e0 irq_exit_rcu+0xe/0x20 sysvec_apic_timer_interrupt+0x6c/0x80 asm_sysvec_apic_timer_interrupt+0x1a/0x20 The buggy address belongs to the object at ffff88810bbdcc00 which belongs to the cache kmalloc-64 of size 64 The buggy address is located 45 bytes inside of freed 64-byte region [ffff88810bbdcc00, ffff88810bbdcc40) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10bbdc flags: 0x200000000000000(node=0|zone=2) page_type: f5(slab) raw: 0200000000000000 ffff8881000428c0 dead000000000100 dead000000000122 raw: 0000000000000000 0000000000200020 00000000f5000000 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88810bbdcb00: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc ffff88810bbdcb80: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc >ffff88810bbdcc00: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ^ ffff88810bbdcc80: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ffff88810bbdcd00: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ================================================================== Disabling lock debugging due to kernel taint Fixes: adae20cb2d20 ("Bluetooth: Convert IRK list to RCU") Assisted-by: LLM Signed-off-by: Cen Zhang --- diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c index 209244fd93918..f8c274c21c0f7 100644 --- a/net/bluetooth/hci_core.c +++ b/net/bluetooth/hci_core.c @@ -1317,8 +1317,14 @@ struct smp_irk *hci_add_irk(struct hci_dev *hdev, bdaddr_t *bdaddr, { struct smp_irk *irk; + /* + * Keep the IRK alive until the value and RPA copies are complete. + */ + rcu_read_lock(); irk = hci_find_irk_by_addr(hdev, bdaddr, addr_type); if (!irk) { + rcu_read_unlock(); + irk = kzalloc_obj(*irk); if (!irk) return NULL; @@ -1326,11 +1332,13 @@ struct smp_irk *hci_add_irk(struct hci_dev *hdev, bdaddr_t *bdaddr, bacpy(&irk->bdaddr, bdaddr); irk->addr_type = addr_type; + rcu_read_lock(); list_add_rcu(&irk->list, &hdev->identity_resolving_keys); } memcpy(irk->val, val, 16); bacpy(&irk->rpa, rpa); + rcu_read_unlock(); return irk; }