[PATCH] Bluetooth: bfusb: Fix use-after-free and memory leak in device lifecycle

[PATCH] Bluetooth: bfusb: Fix use-after-free and memory leak in device lifecycle

[Salah Triki]

The driver stores a reference to the `usb_device` structure (`udev`)
in its private data (`data->udev`), which can persist beyond the
immediate context of the `bfusb_probe()` function.

Without proper reference count management, this can lead to two issues:

1. A `use-after-free` scenario if `udev` is accessed after its main
   reference count drops to zero (e.g., if the device is disconnected
   and the `data` structure is still active).
2. A `memory leak` if `udev`'s reference count is not properly
   decremented during driver disconnect, preventing the `usb_device`
   object from being freed.

To correctly manage the `udev` lifetime, explicitly increment its
reference count with `usb_get_dev(udev)` when storing it in the
driver's private data. Correspondingly, decrement the reference count
with `usb_put_dev(data->udev)` in the `bfusb_disconnect()` callback.

This ensures `udev` remains valid while referenced by the driver's
private data and is properly released when no longer needed.

Signed-off-by: Salah Triki <salah.triki@gmail.com>
---
 drivers/bluetooth/bfusb.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/bluetooth/bfusb.c b/drivers/bluetooth/bfusb.c
index 8df310983bf6..f966bd8361b0 100644
--- a/drivers/bluetooth/bfusb.c
+++ b/drivers/bluetooth/bfusb.c
@@ -622,7 +622,7 @@ static int bfusb_probe(struct usb_interface *intf, const struct usb_device_id *i
 	if (!data)
 		return -ENOMEM;
 
-	data->udev = udev;
+	data->udev = usb_get_dev(udev);
 	data->bulk_in_ep    = bulk_in_ep->desc.bEndpointAddress;
 	data->bulk_out_ep   = bulk_out_ep->desc.bEndpointAddress;
 	data->bulk_pkt_size = le16_to_cpu(bulk_out_ep->desc.wMaxPacketSize);
@@ -701,6 +701,8 @@ static void bfusb_disconnect(struct usb_interface *intf)
 
 	usb_set_intfdata(intf, NULL);
 
+	usb_put_dev(data->udev);
+
 	bfusb_close(hdev);
 
 	hci_unregister_dev(hdev);
-- 
2.43.0

RE: Bluetooth: bfusb: Fix use-after-free and memory leak in device lifecycle

[bluez.test.bot]

[-- Attachment #1: Type: text/plain, Size: 2028 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=986088

---Test result---

Test Summary:
CheckPatch                    PENDING   0.31 seconds
GitLint                       PENDING   0.25 seconds
SubjectPrefix                 PASS      0.10 seconds
BuildKernel                   PASS      24.04 seconds
CheckAllWarning               PASS      26.67 seconds
CheckSparse                   PASS      30.04 seconds
BuildKernel32                 PASS      24.31 seconds
TestRunnerSetup               PASS      475.79 seconds
TestRunner_l2cap-tester       PASS      24.80 seconds
TestRunner_iso-tester         PASS      35.94 seconds
TestRunner_bnep-tester        PASS      5.95 seconds
TestRunner_mgmt-tester        PASS      127.54 seconds
TestRunner_rfcomm-tester      PASS      9.30 seconds
TestRunner_sco-tester         PASS      14.57 seconds
TestRunner_ioctl-tester       PASS      10.00 seconds
TestRunner_mesh-tester        FAIL      11.34 seconds
TestRunner_smp-tester         PASS      8.61 seconds
TestRunner_userchan-tester    PASS      6.13 seconds
IncrementalBuild              PENDING   0.77 seconds

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

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

##############################
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    2.076 seconds
Mesh - Send cancel - 2                               Timed out    1.996 seconds
##############################
Test: IncrementalBuild - PENDING
Desc: Incremental build with the patches in the series
Output:



---
Regards,
Linux Bluetooth

Re: [PATCH] Bluetooth: bfusb: Fix use-after-free and memory leak in device lifecycle

[Markus Elfring]

…
> This ensures `udev` remains valid while referenced by the driver's
> private data and is properly released when no longer needed.

How do you think about to add any tags (like “Fixes” and “Cc”) accordingly?
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?h=v6.16-rc7#n145

Regards,
Markus