2024-01-04 11:57:23

by Ying Hsu

Subject: [PATCH] Bluetooth: Avoid potential use-after-free in hci_error_reset

While handling the HCI_EV_HARDWARE_ERROR event, if the underlying
BT controller is not responding, the GPIO reset mechanism would
free the hci_dev and lead to a use-after-free in hci_error_reset.

Here's the call trace observed on a ChromeOS device with Intel AX201:
queue_work_on+0x3e/0x6c
__hci_cmd_sync_sk+0x2ee/0x4c0 [bluetooth <HASH:3b4a6>]
? init_wait_entry+0x31/0x31
__hci_cmd_sync+0x16/0x20 [bluetooth <HASH:3b4a 6>]
hci_error_reset+0x4f/0xa4 [bluetooth <HASH:3b4a 6>]
process_one_work+0x1d8/0x33f
worker_thread+0x21b/0x373
kthread+0x13a/0x152
? pr_cont_work+0x54/0x54
? kthread_blkcg+0x31/0x31
ret_from_fork+0x1f/0x30

This patch holds the reference count on the hci_dev while processing
a HCI_EV_HARDWARE_ERROR event to avoid potential crash.

Signed-off-by: Ying Hsu <[email protected]>
---
Tested this commit on a chromebook with Intel BT controller.

net/bluetooth/hci_core.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 65601aa52e0d..a42417926028 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -1049,6 +1049,7 @@ static void hci_error_reset(struct work_struct *work)
{
struct hci_dev *hdev = container_of(work, struct hci_dev, error_reset);

+ hci_dev_hold(hdev);
BT_DBG("%s", hdev->name);

if (hdev->hw_error)
@@ -1060,6 +1061,7 @@ static void hci_error_reset(struct work_struct *work)
return;

hci_dev_do_open(hdev);
+ hci_dev_put(hdev);
}

void hci_uuids_clear(struct hci_dev *hdev)
--
2.43.0.472.g3155946c3a-goog

2024-01-04 22:20:54

by patchwork-bot+bluetooth

Subject: Re: [PATCH] Bluetooth: Avoid potential use-after-free in hci_error_reset

Hello:

This patch was applied to bluetooth/bluetooth-next.git (master)
by Luiz Augusto von Dentz <[email protected]>:

On Thu, 4 Jan 2024 11:56:32 +0000 you wrote:
> While handling the HCI_EV_HARDWARE_ERROR event, if the underlying
> BT controller is not responding, the GPIO reset mechanism would
> free the hci_dev and lead to a use-after-free in hci_error_reset.
>
> Here's the call trace observed on a ChromeOS device with Intel AX201:
> queue_work_on+0x3e/0x6c
> __hci_cmd_sync_sk+0x2ee/0x4c0 [bluetooth <HASH:3b4a6>]
> ? init_wait_entry+0x31/0x31
> __hci_cmd_sync+0x16/0x20 [bluetooth <HASH:3b4a 6>]
> hci_error_reset+0x4f/0xa4 [bluetooth <HASH:3b4a 6>]
> process_one_work+0x1d8/0x33f
> worker_thread+0x21b/0x373
> kthread+0x13a/0x152
> ? pr_cont_work+0x54/0x54
> ? kthread_blkcg+0x31/0x31
> ret_from_fork+0x1f/0x30
>
> [...]

Here is the summary with links:
- Bluetooth: Avoid potential use-after-free in hci_error_reset
https://git.kernel.org/bluetooth/bluetooth-next/c/c6d011a4e7d3

You are awesome, thank you!
--
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2024-01-05 15:37:05

by Luiz Augusto von Dentz

Subject: Re: [PATCH] Bluetooth: Avoid potential use-after-free in hci_error_reset

Hi Christophe,

On Fri, Jan 5, 2024 at 2:15 AM Christophe JAILLET
<[email protected]> wrote:
>
> Le 04/01/2024 à 12:56, Ying Hsu a écrit :
> > While handling the HCI_EV_HARDWARE_ERROR event, if the underlying
> > BT controller is not responding, the GPIO reset mechanism would
> > free the hci_dev and lead to a use-after-free in hci_error_reset.
> >
> > Here's the call trace observed on a ChromeOS device with Intel AX201:
> > queue_work_on+0x3e/0x6c
> > __hci_cmd_sync_sk+0x2ee/0x4c0 [bluetooth <HASH:3b4a6>]
> > ? init_wait_entry+0x31/0x31
> > __hci_cmd_sync+0x16/0x20 [bluetooth <HASH:3b4a 6>]
> > hci_error_reset+0x4f/0xa4 [bluetooth <HASH:3b4a 6>]
> > process_one_work+0x1d8/0x33f
> > worker_thread+0x21b/0x373
> > kthread+0x13a/0x152
> > ? pr_cont_work+0x54/0x54
> > ? kthread_blkcg+0x31/0x31
> > ret_from_fork+0x1f/0x30
> >
> > This patch holds the reference count on the hci_dev while processing
> > a HCI_EV_HARDWARE_ERROR event to avoid potential crash.
> >
> > Signed-off-by: Ying Hsu <[email protected]>
> > ---
> > Tested this commit on a chromebook with Intel BT controller.
> >
> > net/bluetooth/hci_core.c | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> > diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
> > index 65601aa52e0d..a42417926028 100644
> > --- a/net/bluetooth/hci_core.c
> > +++ b/net/bluetooth/hci_core.c
> > @@ -1049,6 +1049,7 @@ static void hci_error_reset(struct work_struct *work)
> > {
> > struct hci_dev *hdev = container_of(work, struct hci_dev, error_reset);
> >
> > + hci_dev_hold(hdev);
> > BT_DBG("%s", hdev->name);
> >
> > if (hdev->hw_error)
> > @@ -1060,6 +1061,7 @@ static void hci_error_reset(struct work_struct *work)
> > return;
>
> ^^^^^
> Should we also call hci_dev_put() if we hit this return?

Yep, I will fix that since Ive already pushed to bluetooth-next.

>
> CJ
>
> >
> > hci_dev_do_open(hdev);
> > + hci_dev_put(hdev);
> > }
> >
> > void hci_uuids_clear(struct hci_dev *hdev)
>


--
Luiz Augusto von Dentz

2024-01-05 15:40:42

by Luiz Augusto von Dentz

Subject: Re: [PATCH] Bluetooth: Avoid potential use-after-free in hci_error_reset

Hi,

On Fri, Jan 5, 2024 at 10:36 AM Luiz Augusto von Dentz
<[email protected]> wrote:
>
> Hi Christophe,
>
> On Fri, Jan 5, 2024 at 2:15 AM Christophe JAILLET
> <[email protected]> wrote:
> >
> > Le 04/01/2024 à 12:56, Ying Hsu a écrit :
> > > While handling the HCI_EV_HARDWARE_ERROR event, if the underlying
> > > BT controller is not responding, the GPIO reset mechanism would
> > > free the hci_dev and lead to a use-after-free in hci_error_reset.
> > >
> > > Here's the call trace observed on a ChromeOS device with Intel AX201:
> > > queue_work_on+0x3e/0x6c
> > > __hci_cmd_sync_sk+0x2ee/0x4c0 [bluetooth <HASH:3b4a6>]
> > > ? init_wait_entry+0x31/0x31
> > > __hci_cmd_sync+0x16/0x20 [bluetooth <HASH:3b4a 6>]
> > > hci_error_reset+0x4f/0xa4 [bluetooth <HASH:3b4a 6>]
> > > process_one_work+0x1d8/0x33f
> > > worker_thread+0x21b/0x373
> > > kthread+0x13a/0x152
> > > ? pr_cont_work+0x54/0x54
> > > ? kthread_blkcg+0x31/0x31
> > > ret_from_fork+0x1f/0x30
> > >
> > > This patch holds the reference count on the hci_dev while processing
> > > a HCI_EV_HARDWARE_ERROR event to avoid potential crash.
> > >
> > > Signed-off-by: Ying Hsu <[email protected]>
> > > ---
> > > Tested this commit on a chromebook with Intel BT controller.
> > >
> > > net/bluetooth/hci_core.c | 2 ++
> > > 1 file changed, 2 insertions(+)
> > >
> > > diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
> > > index 65601aa52e0d..a42417926028 100644
> > > --- a/net/bluetooth/hci_core.c
> > > +++ b/net/bluetooth/hci_core.c
> > > @@ -1049,6 +1049,7 @@ static void hci_error_reset(struct work_struct *work)
> > > {
> > > struct hci_dev *hdev = container_of(work, struct hci_dev, error_reset);
> > >
> > > + hci_dev_hold(hdev);
> > > BT_DBG("%s", hdev->name);
> > >
> > > if (hdev->hw_error)
> > > @@ -1060,6 +1061,7 @@ static void hci_error_reset(struct work_struct *work)
> > > return;
> >
> > ^^^^^
> > Should we also call hci_dev_put() if we hit this return?
>
> Yep, I will fix that since Ive already pushed to bluetooth-next.

Here is the proposed change:

- if (hci_dev_do_close(hdev))
- return;
+ if (!hci_dev_do_close(hdev))
+ hci_dev_do_open(hdev);

- hci_dev_do_open(hdev);
+ hci_dev_put(hdev);

> >
> > CJ
> >
> > >
> > > hci_dev_do_open(hdev);
> > > + hci_dev_put(hdev);
> > > }
> > >
> > > void hci_uuids_clear(struct hci_dev *hdev)
> >
>
>
> --
> Luiz Augusto von Dentz



--
Luiz Augusto von Dentz