Bluetooth: MGMT: Fix UAF on mgmt_remove_adv_monitor_complete

This reworks MGMT_OP_REMOVE_ADV_MONITOR to not use mgmt_pending_add to
avoid crashes like bellow:

==================================================================
BUG: KASAN: slab-use-after-free in mgmt_remove_adv_monitor_complete+0xe5/0x540 net/bluetooth/mgmt.c:5406
Read of size 8 at addr ffff88801c53f318 by task kworker/u5:5/5341

CPU: 0 UID: 0 PID: 5341 Comm: kworker/u5:5 Not tainted 6.15.0-syzkaller-10402-g4cb6c8af8591 #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Workqueue: hci0 hci_cmd_sync_work
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0xd2/0x2b0 mm/kasan/report.c:521
 kasan_report+0x118/0x150 mm/kasan/report.c:634
 mgmt_remove_adv_monitor_complete+0xe5/0x540 net/bluetooth/mgmt.c:5406
 hci_cmd_sync_work+0x261/0x3a0 net/bluetooth/hci_sync.c:334
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3321
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3402
 kthread+0x711/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Allocated by task 5987:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:394
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __kmalloc_cache_noprof+0x230/0x3d0 mm/slub.c:4358
 kmalloc_noprof include/linux/slab.h:905 [inline]
 kzalloc_noprof include/linux/slab.h:1039 [inline]
 mgmt_pending_new+0x65/0x240 net/bluetooth/mgmt_util.c:252
 mgmt_pending_add+0x34/0x120 net/bluetooth/mgmt_util.c:279
 remove_adv_monitor+0x103/0x1b0 net/bluetooth/mgmt.c:5454
 hci_mgmt_cmd+0x9c9/0xef0 net/bluetooth/hci_sock.c:1719
 hci_sock_sendmsg+0x6ca/0xef0 net/bluetooth/hci_sock.c:1839
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg+0x219/0x270 net/socket.c:727
 sock_write_iter+0x258/0x330 net/socket.c:1131
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x548/0xa90 fs/read_write.c:686
 ksys_write+0x145/0x250 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 5989:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576
 poison_slab_object mm/kasan/common.c:247 [inline]
 __kasan_slab_free+0x62/0x70 mm/kasan/common.c:264
 kasan_slab_free include/linux/kasan.h:233 [inline]
 slab_free_hook mm/slub.c:2380 [inline]
 slab_free mm/slub.c:4642 [inline]
 kfree+0x18e/0x440 mm/slub.c:4841
 mgmt_pending_foreach+0xc9/0x120 net/bluetooth/mgmt_util.c:242
 mgmt_index_removed+0x10d/0x2f0 net/bluetooth/mgmt.c:9366
 hci_sock_bind+0xbe9/0x1000 net/bluetooth/hci_sock.c:1314
 __sys_bind_socket net/socket.c:1810 [inline]
 __sys_bind+0x2c3/0x3e0 net/socket.c:1841
 __do_sys_bind net/socket.c:1846 [inline]
 __se_sys_bind net/socket.c:1844 [inline]
 __x64_sys_bind+0x7a/0x90 net/socket.c:1844
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Fixes: 66bd095 ("Bluetooth: advmon offload MSFT remove monitor")
Closes: https://syzkaller.appspot.com/bug?extid=feb0dc579bbe30a13190
Reported-by: [email protected]
Tested-by: [email protected]
Signed-off-by: Luiz Augusto von Dentz <[email protected]>

Author: Vudentz

include/net/bluetooth/hci_core.h

@@ -2400,7 +2400,6 @@ void mgmt_advertising_added(struct sock *sk, struct hci_dev *hdev,
 			    u8 instance);
 void mgmt_advertising_removed(struct sock *sk, struct hci_dev *hdev,
 			      u8 instance);
-void mgmt_adv_monitor_removed(struct hci_dev *hdev, u16 handle);
 int mgmt_phy_configuration_changed(struct hci_dev *hdev, struct sock *skip);
 void mgmt_adv_monitor_device_lost(struct hci_dev *hdev, u16 handle,
 				  bdaddr_t *bdaddr, u8 addr_type);

net/bluetooth/hci_core.c

@@ -1877,10 +1877,8 @@ void hci_free_adv_monitor(struct hci_dev *hdev, struct adv_monitor *monitor)
 	if (monitor->handle)
 		idr_remove(&hdev->adv_monitors_idr, monitor->handle);
 
-	if (monitor->state != ADV_MONITOR_STATE_NOT_REGISTERED) {
+	if (monitor->state != ADV_MONITOR_STATE_NOT_REGISTERED)
 		hdev->adv_monitors_cnt--;
-		mgmt_adv_monitor_removed(hdev, monitor->handle);
-	}
 
 	kfree(monitor);
 }

net/bluetooth/mgmt.c

@@ -5108,24 +5108,14 @@ static void mgmt_adv_monitor_added(struct sock *sk, struct hci_dev *hdev,
 	mgmt_event(MGMT_EV_ADV_MONITOR_ADDED, hdev, &ev, sizeof(ev), sk);
 }
 
-void mgmt_adv_monitor_removed(struct hci_dev *hdev, u16 handle)
+static void mgmt_adv_monitor_removed(struct sock *sk, struct hci_dev *hdev,
+				     u16 handle)
 {
 	struct mgmt_ev_adv_monitor_removed ev;
-	struct mgmt_pending_cmd *cmd;
-	struct sock *sk_skip = NULL;
-	struct mgmt_cp_remove_adv_monitor *cp;
-
-	cmd = pending_find(MGMT_OP_REMOVE_ADV_MONITOR, hdev);
-	if (cmd) {
-		cp = cmd->param;
-
-		if (cp->monitor_handle)
-			sk_skip = cmd->sk;
-	}
 
 	ev.monitor_handle = cpu_to_le16(handle);
 
-	mgmt_event(MGMT_EV_ADV_MONITOR_REMOVED, hdev, &ev, sizeof(ev), sk_skip);
+	mgmt_event(MGMT_EV_ADV_MONITOR_REMOVED, hdev, &ev, sizeof(ev), sk);
 }
 
 static int read_adv_mon_features(struct sock *sk, struct hci_dev *hdev,
@@ -5227,8 +5217,7 @@ static int __add_adv_patterns_monitor(struct sock *sk, struct hci_dev *hdev,
 
 	if (pending_find(MGMT_OP_SET_LE, hdev) ||
 	    pending_find(MGMT_OP_ADD_ADV_PATTERNS_MONITOR, hdev) ||
-	    pending_find(MGMT_OP_ADD_ADV_PATTERNS_MONITOR_RSSI, hdev) ||
-	    pending_find(MGMT_OP_REMOVE_ADV_MONITOR, hdev)) {
+	    pending_find(MGMT_OP_ADD_ADV_PATTERNS_MONITOR_RSSI, hdev)) {
 		status = MGMT_STATUS_BUSY;
 		goto unlock;
 	}
@@ -5398,8 +5387,7 @@ static void mgmt_remove_adv_monitor_complete(struct hci_dev *hdev,
 	struct mgmt_pending_cmd *cmd = data;
 	struct mgmt_cp_remove_adv_monitor *cp;
 
-	if (status == -ECANCELED ||
-	    cmd != pending_find(MGMT_OP_REMOVE_ADV_MONITOR, hdev))
+	if (status == -ECANCELED)
 		return;
 
 	hci_dev_lock(hdev);
@@ -5408,12 +5396,14 @@ static void mgmt_remove_adv_monitor_complete(struct hci_dev *hdev,
 
 	rp.monitor_handle = cp->monitor_handle;
 
-	if (!status)
+	if (!status) {
+		mgmt_adv_monitor_removed(cmd->sk, hdev, cp->monitor_handle);
 		hci_update_passive_scan(hdev);
+	}
 
 	mgmt_cmd_complete(cmd->sk, cmd->index, cmd->opcode,
 			  mgmt_status(status), &rp, sizeof(rp));
-	mgmt_pending_remove(cmd);
+	mgmt_pending_free(cmd);
 
 	hci_dev_unlock(hdev);
 	bt_dev_dbg(hdev, "remove monitor %d complete, status %d",
@@ -5423,10 +5413,6 @@ static void mgmt_remove_adv_monitor_complete(struct hci_dev *hdev,
 static int mgmt_remove_adv_monitor_sync(struct hci_dev *hdev, void *data)
 {
 	struct mgmt_pending_cmd *cmd = data;
-
-	if (cmd != pending_find(MGMT_OP_REMOVE_ADV_MONITOR, hdev))
-		return -ECANCELED;
-
 	struct mgmt_cp_remove_adv_monitor *cp = cmd->param;
 	u16 handle = __le16_to_cpu(cp->monitor_handle);
 
@@ -5445,14 +5431,13 @@ static int remove_adv_monitor(struct sock *sk, struct hci_dev *hdev,
 	hci_dev_lock(hdev);
 
 	if (pending_find(MGMT_OP_SET_LE, hdev) ||
-	    pending_find(MGMT_OP_REMOVE_ADV_MONITOR, hdev) ||
 	    pending_find(MGMT_OP_ADD_ADV_PATTERNS_MONITOR, hdev) ||
 	    pending_find(MGMT_OP_ADD_ADV_PATTERNS_MONITOR_RSSI, hdev)) {
 		status = MGMT_STATUS_BUSY;
 		goto unlock;
 	}
 
-	cmd = mgmt_pending_add(sk, MGMT_OP_REMOVE_ADV_MONITOR, hdev, data, len);
+	cmd = mgmt_pending_new(sk, MGMT_OP_REMOVE_ADV_MONITOR, hdev, data, len);
 	if (!cmd) {
 		status = MGMT_STATUS_NO_RESOURCES;
 		goto unlock;
@@ -5462,7 +5447,7 @@ static int remove_adv_monitor(struct sock *sk, struct hci_dev *hdev,
 				  mgmt_remove_adv_monitor_complete);
 
 	if (err) {
-		mgmt_pending_remove(cmd);
+		mgmt_pending_free(cmd);
 
 		if (err == -ENOMEM)
 			status = MGMT_STATUS_NO_RESOURCES;