[PATCH v3] Bluetooth: fix use-after-free in device_for_each_child()

[PATCH v3] Bluetooth: fix use-after-free in device_for_each_child()

[Luiz Augusto von Dentz]

From: Dmitry Antipov <dmantipov@yandex.ru>

Syzbot has reported the following KASAN splat:

BUG: KASAN: slab-use-after-free in device_for_each_child+0x18f/0x1a0
Read of size 8 at addr ffff88801f605308 by task kbnepd bnep0/4980

CPU: 0 UID: 0 PID: 4980 Comm: kbnepd bnep0 Not tainted 6.12.0-rc4-00161-gae90f6a6170d #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-2.fc40 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x100/0x190
 ? device_for_each_child+0x18f/0x1a0
 print_report+0x13a/0x4cb
 ? __virt_addr_valid+0x5e/0x590
 ? __phys_addr+0xc6/0x150
 ? device_for_each_child+0x18f/0x1a0
 kasan_report+0xda/0x110
 ? device_for_each_child+0x18f/0x1a0
 ? __pfx_dev_memalloc_noio+0x10/0x10
 device_for_each_child+0x18f/0x1a0
 ? __pfx_device_for_each_child+0x10/0x10
 pm_runtime_set_memalloc_noio+0xf2/0x180
 netdev_unregister_kobject+0x1ed/0x270
 unregister_netdevice_many_notify+0x123c/0x1d80
 ? __mutex_trylock_common+0xde/0x250
 ? __pfx_unregister_netdevice_many_notify+0x10/0x10
 ? trace_contention_end+0xe6/0x140
 ? __mutex_lock+0x4e7/0x8f0
 ? __pfx_lock_acquire.part.0+0x10/0x10
 ? rcu_is_watching+0x12/0xc0
 ? unregister_netdev+0x12/0x30
 unregister_netdevice_queue+0x30d/0x3f0
 ? __pfx_unregister_netdevice_queue+0x10/0x10
 ? __pfx_down_write+0x10/0x10
 unregister_netdev+0x1c/0x30
 bnep_session+0x1fb3/0x2ab0
 ? __pfx_bnep_session+0x10/0x10
 ? __pfx_lock_release+0x10/0x10
 ? __pfx_woken_wake_function+0x10/0x10
 ? __kthread_parkme+0x132/0x200
 ? __pfx_bnep_session+0x10/0x10
 ? kthread+0x13a/0x370
 ? __pfx_bnep_session+0x10/0x10
 kthread+0x2b7/0x370
 ? __pfx_kthread+0x10/0x10
 ret_from_fork+0x48/0x80
 ? __pfx_kthread+0x10/0x10
 ret_from_fork_asm+0x1a/0x30
 </TASK>

Allocated by task 4974:
 kasan_save_stack+0x30/0x50
 kasan_save_track+0x14/0x30
 __kasan_kmalloc+0xaa/0xb0
 __kmalloc_noprof+0x1d1/0x440
 hci_alloc_dev_priv+0x1d/0x2820
 __vhci_create_device+0xef/0x7d0
 vhci_write+0x2c7/0x480
 vfs_write+0x6a0/0xfc0
 ksys_write+0x12f/0x260
 do_syscall_64+0xc7/0x250
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 4979:
 kasan_save_stack+0x30/0x50
 kasan_save_track+0x14/0x30
 kasan_save_free_info+0x3b/0x60
 __kasan_slab_free+0x4f/0x70
 kfree+0x141/0x490
 hci_release_dev+0x4d9/0x600
 bt_host_release+0x6a/0xb0
 device_release+0xa4/0x240
 kobject_put+0x1ec/0x5a0
 put_device+0x1f/0x30
 vhci_release+0x81/0xf0
 __fput+0x3f6/0xb30
 task_work_run+0x151/0x250
 do_exit+0xa79/0x2c30
 do_group_exit+0xd5/0x2a0
 get_signal+0x1fcd/0x2210
 arch_do_signal_or_restart+0x93/0x780
 syscall_exit_to_user_mode+0x140/0x290
 do_syscall_64+0xd4/0x250
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

In 'hci_conn_del_sysfs()', 'device_unregister()' may be called when
an underlying (kobject) reference counter is greater than 1. This
means that reparenting (happened when the device is actually freed)
is delayed and, during that delay, parent controller device (hciX)
may be deleted. Since the latter may create a dangling pointer to
freed parent, avoid that scenario by reparenting to NULL explicitly.

Reported-by: syzbot+6cf5652d3df49fae2e3f@syzkaller.appspotmail.com
Tested-by: syzbot+6cf5652d3df49fae2e3f@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=6cf5652d3df49fae2e3f
Fixes: a85fb91e3d72 ("Bluetooth: Fix double free in hci_conn_cleanup")
Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
---
 net/bluetooth/hci_sysfs.c | 15 ++++-----------
 1 file changed, 4 insertions(+), 11 deletions(-)

diff --git a/net/bluetooth/hci_sysfs.c b/net/bluetooth/hci_sysfs.c
index 367e32fe30eb..4b54dbbf0729 100644
--- a/net/bluetooth/hci_sysfs.c
+++ b/net/bluetooth/hci_sysfs.c
@@ -21,16 +21,6 @@ static const struct device_type bt_link = {
 	.release = bt_link_release,
 };
 
-/*
- * The rfcomm tty device will possibly retain even when conn
- * is down, and sysfs doesn't support move zombie device,
- * so we should move the device before conn device is destroyed.
- */
-static int __match_tty(struct device *dev, void *data)
-{
-	return !strncmp(dev_name(dev), "rfcomm", 6);
-}
-
 void hci_conn_init_sysfs(struct hci_conn *conn)
 {
 	struct hci_dev *hdev = conn->hdev;
@@ -73,10 +63,13 @@ void hci_conn_del_sysfs(struct hci_conn *conn)
 		return;
 	}
 
+	/* If there are devices using the connection as parent reset it to NULL
+	 * before unregistering the device.
+	 */
 	while (1) {
 		struct device *dev;
 
-		dev = device_find_child(&conn->dev, NULL, __match_tty);
+		dev = device_find_any_child(&conn->dev);
 		if (!dev)
 			break;
 		device_move(dev, NULL, DPM_ORDER_DEV_LAST);
-- 
2.47.0

RE: [v3] Bluetooth: fix use-after-free in device_for_each_child()

[bluez.test.bot]

[-- Attachment #1: Type: text/plain, Size: 2002 bytes --]

This is automated email and please do not reply to this email!

Dear submitter,

Thank you for submitting the patches to the linux bluetooth mailing list.
This is a CI test results with your patch series:
PW Link:https://patchwork.kernel.org/project/bluetooth/list/?series=909346

---Test result---

Test Summary:
CheckPatch                    PENDING   0.37 seconds
GitLint                       PENDING   0.19 seconds
SubjectPrefix                 PASS      0.12 seconds
BuildKernel                   PASS      25.59 seconds
CheckAllWarning               PASS      27.37 seconds
CheckSparse                   PASS      34.08 seconds
BuildKernel32                 PASS      24.67 seconds
TestRunnerSetup               PASS      449.74 seconds
TestRunner_l2cap-tester       PASS      25.07 seconds
TestRunner_iso-tester         FAIL      32.59 seconds
TestRunner_bnep-tester        PASS      4.83 seconds
TestRunner_mgmt-tester        PASS      127.95 seconds
TestRunner_rfcomm-tester      PASS      8.19 seconds
TestRunner_sco-tester         PASS      12.69 seconds
TestRunner_ioctl-tester       PASS      8.48 seconds
TestRunner_mesh-tester        PASS      6.25 seconds
TestRunner_smp-tester         PASS      7.92 seconds
TestRunner_userchan-tester    PASS      4.98 seconds
IncrementalBuild              PENDING   0.80 seconds

Details
##############################
Test: CheckPatch - PENDING
Desc: Run checkpatch.pl script
Output:

##############################
Test: GitLint - PENDING
Desc: Run gitlint
Output:

##############################
Test: TestRunner_iso-tester - FAIL
Desc: Run iso-tester with test-runner
Output:
WARNING: possible circular locking dependency detected
Total: 124, Passed: 119 (96.0%), Failed: 1, Not Run: 4

Failed Test Cases
ISO Connect2 Suspend - Success                       Failed       4.238 seconds
##############################
Test: IncrementalBuild - PENDING
Desc: Incremental build with the patches in the series
Output:



---
Regards,
Linux Bluetooth

Re: [PATCH v3] Bluetooth: fix use-after-free in device_for_each_child()

[patchwork-bot+bluetooth]

Hello:

This patch was applied to bluetooth/bluetooth-next.git (master)
by Luiz Augusto von Dentz <luiz.von.dentz@intel.com>:

On Wed, 13 Nov 2024 11:09:49 -0500 you wrote:
> From: Dmitry Antipov <dmantipov@yandex.ru>
> 
> Syzbot has reported the following KASAN splat:
> 
> BUG: KASAN: slab-use-after-free in device_for_each_child+0x18f/0x1a0
> Read of size 8 at addr ffff88801f605308 by task kbnepd bnep0/4980
> 
> [...]

Here is the summary with links:
  - [v3] Bluetooth: fix use-after-free in device_for_each_child()
    https://git.kernel.org/bluetooth/bluetooth-next/c/29186974d7f0

You are awesome, thank you!
-- 
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