[PATCH] Bluetooth: btusb: revert use of devm_kzalloc in btusb

[PATCH] Bluetooth: btusb: revert use of devm_kzalloc in btusb

[Raphael Pinsonneault-Thibeault]

This reverts commit 98921dbd00c4e ("Bluetooth: Use devm_kzalloc in
btusb.c file").

In btusb_probe(), we use devm_kzalloc() to allocate the btusb data. This
ties the lifetime of all the btusb data to the binding of a driver to
one interface, INTF. In a driver that binds to other interfaces, ISOC
and DIAG, this is an accident waiting to happen.

The issue is revealed in btusb_disconnect(), where calling
usb_driver_release_interface(&btusb_driver, data->intf) will have devm
free the data that is also being used by the other interfaces of the
driver that may not be released yet.

To fix this, revert the use of devm and go back to freeing memory
explicitly.

Signed-off-by: Raphael Pinsonneault-Thibeault <rpthibeault@gmail.com>
---
Syzbot reported this UAF already and my commit 23d22f2f7176
("Bluetooth: btusb: reorder cleanup in btusb_disconnect to avoid UAF")
provided a fix that rearranged the
usb_driver_release_interface() calls so INTF was released last because
I (wrongly) assumed using devm like this was intentional.

This patch is motivated by a discussion prompted by Oliver Neukum:
https://lore.kernel.org/linux-bluetooth/aee37797-a280-47ea-91ac-487ddc124ac7@neukum.org/

link to patch for 23d22f2f7176:
https://lore.kernel.org/linux-bluetooth/20251105192839.895418-3-rpthibeault@gmail.com/

 drivers/bluetooth/btusb.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
index 8ed3883ab8ee..ded09e94d296 100644
--- a/drivers/bluetooth/btusb.c
+++ b/drivers/bluetooth/btusb.c
@@ -4052,7 +4052,7 @@ static int btusb_probe(struct usb_interface *intf,
 			return -ENODEV;
 	}
 
-	data = devm_kzalloc(&intf->dev, sizeof(*data), GFP_KERNEL);
+	data = kzalloc(sizeof(*data), GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;
 
@@ -4075,8 +4075,10 @@ static int btusb_probe(struct usb_interface *intf,
 		}
 	}
 
-	if (!data->intr_ep || !data->bulk_tx_ep || !data->bulk_rx_ep)
+	if (!data->intr_ep || !data->bulk_tx_ep || !data->bulk_rx_ep) {
+		kfree(data);
 		return -ENODEV;
+	}
 
 	if (id->driver_info & BTUSB_AMP) {
 		data->cmdreq_type = USB_TYPE_CLASS | 0x01;
@@ -4131,8 +4133,10 @@ static int btusb_probe(struct usb_interface *intf,
 	data->recv_acl = hci_recv_frame;
 
 	hdev = hci_alloc_dev_priv(priv_size);
-	if (!hdev)
+	if (!hdev) {
+		kfree(data);
 		return -ENOMEM;
+	}
 
 	hdev->bus = HCI_USB;
 	hci_set_drvdata(hdev, data);
@@ -4406,6 +4410,7 @@ static int btusb_probe(struct usb_interface *intf,
 	if (data->reset_gpio)
 		gpiod_put(data->reset_gpio);
 	hci_free_dev(hdev);
+	kfree(data);
 	return err;
 }
 
@@ -4454,6 +4459,7 @@ static void btusb_disconnect(struct usb_interface *intf)
 	}
 
 	hci_free_dev(hdev);
+	kfree(data);
 }
 
 #ifdef CONFIG_PM

base-commit: 9d588a1140b9ae211581a7a154d0b806d8cd8238
-- 
2.43.0

RE: Bluetooth: btusb: revert use of devm_kzalloc in btusb

[bluez.test.bot]

[-- Attachment #1: Type: text/plain, Size: 2672 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=1032047

---Test result---

Test Summary:
CheckPatch                    PENDING   0.36 seconds
GitLint                       PENDING   0.28 seconds
SubjectPrefix                 PASS      0.09 seconds
BuildKernel                   PASS      23.24 seconds
CheckAllWarning               PASS      25.56 seconds
CheckSparse                   PASS      29.18 seconds
BuildKernel32                 PASS      23.11 seconds
TestRunnerSetup               PASS      514.56 seconds
TestRunner_l2cap-tester       PASS      25.17 seconds
TestRunner_iso-tester         PASS      65.92 seconds
TestRunner_bnep-tester        PASS      6.02 seconds
TestRunner_mgmt-tester        FAIL      112.82 seconds
TestRunner_rfcomm-tester      PASS      8.91 seconds
TestRunner_sco-tester         FAIL      13.64 seconds
TestRunner_ioctl-tester       PASS      9.32 seconds
TestRunner_mesh-tester        FAIL      11.44 seconds
TestRunner_smp-tester         PASS      8.10 seconds
TestRunner_userchan-tester    PASS      6.06 seconds
IncrementalBuild              PENDING   0.67 seconds

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

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

##############################
Test: TestRunner_mgmt-tester - FAIL
Desc: Run mgmt-tester with test-runner
Output:
Total: 494, Passed: 488 (98.8%), Failed: 2, Not Run: 4

Failed Test Cases
Read Exp Feature - Success                           Failed       0.106 seconds
LL Privacy - Set Device Flag 1 (Device Privacy)      Failed       0.170 seconds
##############################
Test: TestRunner_sco-tester - FAIL
Desc: Run sco-tester with test-runner
Output:
WARNING: possible circular locking dependency detected
BUG: sleeping function called from invalid context at net/core/sock.c:3782
Total: 30, Passed: 30 (100.0%), Failed: 0, Not Run: 0
##############################
Test: TestRunner_mesh-tester - FAIL
Desc: Run mesh-tester with test-runner
Output:
Total: 10, Passed: 8 (80.0%), Failed: 2, Not Run: 0

Failed Test Cases
Mesh - Send cancel - 1                               Timed out    2.318 seconds
Mesh - Send cancel - 2                               Timed out    1.995 seconds
##############################
Test: IncrementalBuild - PENDING
Desc: Incremental build with the patches in the series
Output:



---
Regards,
Linux Bluetooth

Re: [PATCH] Bluetooth: btusb: revert use of devm_kzalloc in btusb

[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, 10 Dec 2025 11:02:28 -0500 you wrote:
> This reverts commit 98921dbd00c4e ("Bluetooth: Use devm_kzalloc in
> btusb.c file").
> 
> In btusb_probe(), we use devm_kzalloc() to allocate the btusb data. This
> ties the lifetime of all the btusb data to the binding of a driver to
> one interface, INTF. In a driver that binds to other interfaces, ISOC
> and DIAG, this is an accident waiting to happen.
> 
> [...]

Here is the summary with links:
  - Bluetooth: btusb: revert use of devm_kzalloc in btusb
    https://git.kernel.org/bluetooth/bluetooth-next/c/3a7cf69ce3cf

You are awesome, thank you!
-- 
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