[PATCH v2 bluetooth-next] Bluetooth: vhci: Prevent use-after-free by removing debugfs files early

[PATCH v2 bluetooth-next] Bluetooth: vhci: Prevent use-after-free by removing debugfs files early

[Ivan Pravdin]

Move the creation of debugfs files into a dedicated function, and ensure
they are explicitly removed during vhci_release(), before associated
data structures are freed.

Previously, debugfs files such as "force_suspend", "force_wakeup", and
others were created under hdev->debugfs but not removed in
vhci_release(). Since vhci_release() frees the backing vhci_data
structure, any access to these files after release would result in
use-after-free errors.

Although hdev->debugfs is later freed in hci_release_dev(), user can
access files after vhci_data is freed but before hdev->debugfs is
released.

Fixes: ab4e4380d4e1 ("Bluetooth: Add vhci devcoredump support")
Signed-off-by: Ivan Pravdin <ipravdin.official@gmail.com>
Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>
---
changes v1 -> v2:
    - Fixed tag order

v1: https://lore.kernel.org/all/20250716004252.125466-2-ipravdin.official@gmail.com/

 drivers/bluetooth/hci_vhci.c | 57 ++++++++++++++++++++++++++----------
 1 file changed, 41 insertions(+), 16 deletions(-)

diff --git a/drivers/bluetooth/hci_vhci.c b/drivers/bluetooth/hci_vhci.c
index f7d8c3c00655..2fef08254d78 100644
--- a/drivers/bluetooth/hci_vhci.c
+++ b/drivers/bluetooth/hci_vhci.c
@@ -380,6 +380,28 @@ static const struct file_operations force_devcoredump_fops = {
 	.write		= force_devcd_write,
 };
 
+static void vhci_debugfs_init(struct vhci_data *data)
+{
+	struct hci_dev *hdev = data->hdev;
+
+	debugfs_create_file("force_suspend", 0644, hdev->debugfs, data,
+			    &force_suspend_fops);
+
+	debugfs_create_file("force_wakeup", 0644, hdev->debugfs, data,
+			    &force_wakeup_fops);
+
+	if (IS_ENABLED(CONFIG_BT_MSFTEXT))
+		debugfs_create_file("msft_opcode", 0644, hdev->debugfs, data,
+				    &msft_opcode_fops);
+
+	if (IS_ENABLED(CONFIG_BT_AOSPEXT))
+		debugfs_create_file("aosp_capable", 0644, hdev->debugfs, data,
+				    &aosp_capable_fops);
+
+	debugfs_create_file("force_devcoredump", 0644, hdev->debugfs, data,
+			    &force_devcoredump_fops);
+}
+
 static int __vhci_create_device(struct vhci_data *data, __u8 opcode)
 {
 	struct hci_dev *hdev;
@@ -434,22 +456,8 @@ static int __vhci_create_device(struct vhci_data *data, __u8 opcode)
 		return -EBUSY;
 	}
 
-	debugfs_create_file("force_suspend", 0644, hdev->debugfs, data,
-			    &force_suspend_fops);
-
-	debugfs_create_file("force_wakeup", 0644, hdev->debugfs, data,
-			    &force_wakeup_fops);
-
-	if (IS_ENABLED(CONFIG_BT_MSFTEXT))
-		debugfs_create_file("msft_opcode", 0644, hdev->debugfs, data,
-				    &msft_opcode_fops);
-
-	if (IS_ENABLED(CONFIG_BT_AOSPEXT))
-		debugfs_create_file("aosp_capable", 0644, hdev->debugfs, data,
-				    &aosp_capable_fops);
-
-	debugfs_create_file("force_devcoredump", 0644, hdev->debugfs, data,
-			    &force_devcoredump_fops);
+	if (!IS_ERR_OR_NULL(hdev->debugfs))
+		vhci_debugfs_init(data);
 
 	hci_skb_pkt_type(skb) = HCI_VENDOR_PKT;
 
@@ -651,6 +659,21 @@ static int vhci_open(struct inode *inode, struct file *file)
 	return 0;
 }
 
+static void vhci_debugfs_remove(struct hci_dev *hdev)
+{
+	debugfs_lookup_and_remove("force_suspend", hdev->debugfs);
+
+	debugfs_lookup_and_remove("force_wakeup", hdev->debugfs);
+
+	if (IS_ENABLED(CONFIG_BT_MSFTEXT))
+		debugfs_lookup_and_remove("msft_opcode", hdev->debugfs);
+
+	if (IS_ENABLED(CONFIG_BT_AOSPEXT))
+		debugfs_lookup_and_remove("aosp_capable", hdev->debugfs);
+
+	debugfs_lookup_and_remove("force_devcoredump", hdev->debugfs);
+}
+
 static int vhci_release(struct inode *inode, struct file *file)
 {
 	struct vhci_data *data = file->private_data;
@@ -662,6 +685,8 @@ static int vhci_release(struct inode *inode, struct file *file)
 	hdev = data->hdev;
 
 	if (hdev) {
+		if (!IS_ERR_OR_NULL(hdev->debugfs))
+			vhci_debugfs_remove(hdev);
 		hci_unregister_dev(hdev);
 		hci_free_dev(hdev);
 	}
-- 
2.48.1

RE: [v2,bluetooth-next] Bluetooth: vhci: Prevent use-after-free by removing debugfs files early

[bluez.test.bot]

[-- Attachment #1: Type: text/plain, Size: 2455 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=996097

---Test result---

Test Summary:
CheckPatch                    PENDING   0.50 seconds
GitLint                       PENDING   0.42 seconds
SubjectPrefix                 PASS      0.07 seconds
BuildKernel                   PASS      24.32 seconds
CheckAllWarning               PASS      26.98 seconds
CheckSparse                   PASS      30.91 seconds
BuildKernel32                 PASS      24.60 seconds
TestRunnerSetup               PASS      479.96 seconds
TestRunner_l2cap-tester       PASS      24.69 seconds
TestRunner_iso-tester         PASS      38.42 seconds
TestRunner_bnep-tester        PASS      5.98 seconds
TestRunner_mgmt-tester        FAIL      128.72 seconds
TestRunner_rfcomm-tester      PASS      9.25 seconds
TestRunner_sco-tester         PASS      14.47 seconds
TestRunner_ioctl-tester       PASS      9.90 seconds
TestRunner_mesh-tester        FAIL      11.45 seconds
TestRunner_smp-tester         PASS      8.57 seconds
TestRunner_userchan-tester    PASS      6.22 seconds
IncrementalBuild              PENDING   0.99 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: 490, Passed: 483 (98.6%), Failed: 3, Not Run: 4

Failed Test Cases
Read Exp Feature - Success                           Failed       0.105 seconds
LL Privacy - Add Device 2 (2 Devices to AL)          Failed       0.176 seconds
LL Privacy - Set Device Flag 1 (Device Privacy)      Failed       0.164 seconds
##############################
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    2.196 seconds
Mesh - Send cancel - 2                               Timed out    1.997 seconds
##############################
Test: IncrementalBuild - PENDING
Desc: Incremental build with the patches in the series
Output:



---
Regards,
Linux Bluetooth

Re: [PATCH v2 bluetooth-next] Bluetooth: vhci: Prevent use-after-free by removing debugfs files early

[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, 27 Aug 2025 10:53:25 -0400 you wrote:
> Move the creation of debugfs files into a dedicated function, and ensure
> they are explicitly removed during vhci_release(), before associated
> data structures are freed.
> 
> Previously, debugfs files such as "force_suspend", "force_wakeup", and
> others were created under hdev->debugfs but not removed in
> vhci_release(). Since vhci_release() frees the backing vhci_data
> structure, any access to these files after release would result in
> use-after-free errors.
> 
> [...]

Here is the summary with links:
  - [v2,bluetooth-next] Bluetooth: vhci: Prevent use-after-free by removing debugfs files early
    https://git.kernel.org/bluetooth/bluetooth-next/c/c27de1739b83

You are awesome, thank you!
-- 
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