Re: [syzbot] [bluetooth?] KASAN: slab-use-after-free Read in set_powered_sync

[Luiz Augusto von Dentz]

Hi,

On Thu, Oct 3, 2024 at 1:16 PM Qianqiang Liu <qianqiang.liu@xxxxxxx> wrote:
>
> Hi Luiz,
>
> > Are you sure this hasn't been already fixed by Bluetooth: MGMT: Fix
> > possible crash on mgmt_index_removed?
>
> Oh, it looks like it's already fixed by your patch, thanks!
>
> --
> Best,
> Qianqiang Liu
>

#syz test

-- 
Luiz Augusto von Dentz
From eb3ad76a07b6cdaaa156766da5fe6c384a12930b Mon Sep 17 00:00:00 2001
From: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
Date: Thu, 12 Sep 2024 12:34:42 -0400
Subject: [PATCH v1 01/23] Bluetooth: MGMT: Fix possible crash on
 mgmt_index_removed

If mgmt_index_removed is called while there are commands queued on
cmd_sync it could lead to crashes like the bellow trace:

0x0000053D: __list_del_entry_valid_or_report+0x98/0xdc
0x0000053D: mgmt_pending_remove+0x18/0x58 [bluetooth]
0x0000053E: mgmt_remove_adv_monitor_complete+0x80/0x108 [bluetooth]
0x0000053E: hci_cmd_sync_work+0xbc/0x164 [bluetooth]

So while handling mgmt_index_removed this attempts to dequeue
commands passed as user_data to cmd_sync.

Fixes: 7cf5c2978f23 ("Bluetooth: hci_sync: Refactor remove Adv Monitor")
Reported-by: jiaymao <quic_jiaymao@xxxxxxxxxxx>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
---
 net/bluetooth/mgmt.c | 23 ++++++++++++++---------
 1 file changed, 14 insertions(+), 9 deletions(-)

diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
index e4f564d6f6fb..4157d9f23f46 100644
--- a/net/bluetooth/mgmt.c
+++ b/net/bluetooth/mgmt.c
@@ -1453,10 +1453,15 @@ static void cmd_status_rsp(struct mgmt_pending_cmd *cmd, void *data)
 
 static void cmd_complete_rsp(struct mgmt_pending_cmd *cmd, void *data)
 {
-	if (cmd->cmd_complete) {
-		u8 *status = data;
+	struct cmd_lookup *match = data;
 
-		cmd->cmd_complete(cmd, *status);
+	/* dequeue cmd_sync entries using cmd as data as that is about to be
+	 * removed/freed.
+	 */
+	hci_cmd_sync_dequeue(match->hdev, NULL, cmd, NULL);
+
+	if (cmd->cmd_complete) {
+		cmd->cmd_complete(cmd, match->mgmt_status);
 		mgmt_pending_remove(cmd);
 
 		return;
@@ -9394,12 +9399,12 @@ void mgmt_index_added(struct hci_dev *hdev)
 void mgmt_index_removed(struct hci_dev *hdev)
 {
 	struct mgmt_ev_ext_index ev;
-	u8 status = MGMT_STATUS_INVALID_INDEX;
+	struct cmd_lookup match = { NULL, hdev, MGMT_STATUS_INVALID_INDEX };
 
 	if (test_bit(HCI_QUIRK_RAW_DEVICE, &hdev->quirks))
 		return;
 
-	mgmt_pending_foreach(0, hdev, cmd_complete_rsp, &status);
+	mgmt_pending_foreach(0, hdev, cmd_complete_rsp, &match);
 
 	if (hci_dev_test_flag(hdev, HCI_UNCONFIGURED)) {
 		mgmt_index_event(MGMT_EV_UNCONF_INDEX_REMOVED, hdev, NULL, 0,
@@ -9450,7 +9455,7 @@ void mgmt_power_on(struct hci_dev *hdev, int err)
 void __mgmt_power_off(struct hci_dev *hdev)
 {
 	struct cmd_lookup match = { NULL, hdev };
-	u8 status, zero_cod[] = { 0, 0, 0 };
+	u8 zero_cod[] = { 0, 0, 0 };
 
 	mgmt_pending_foreach(MGMT_OP_SET_POWERED, hdev, settings_rsp, &match);
 
@@ -9462,11 +9467,11 @@ void __mgmt_power_off(struct hci_dev *hdev)
 	 * status responses.
 	 */
 	if (hci_dev_test_flag(hdev, HCI_UNREGISTER))
-		status = MGMT_STATUS_INVALID_INDEX;
+		match.mgmt_status = MGMT_STATUS_INVALID_INDEX;
 	else
-		status = MGMT_STATUS_NOT_POWERED;
+		match.mgmt_status = MGMT_STATUS_NOT_POWERED;
 
-	mgmt_pending_foreach(0, hdev, cmd_complete_rsp, &status);
+	mgmt_pending_foreach(0, hdev, cmd_complete_rsp, &match);
 
 	if (memcmp(hdev->dev_class, zero_cod, sizeof(zero_cod)) != 0) {
 		mgmt_limited_event(MGMT_EV_CLASS_OF_DEV_CHANGED, hdev,
-- 
2.46.1