[v1] Bluetooth: HCI: Fix potential null-ptr-deref

[PATCH] Bluetooth: HCI: Fix potential null-ptr-deref

Posted by Sungwoo Kim 1 year, 7 months ago

Dear all,
hci_le_big_sync_established_evt() has a potential null-ptr-deref bug.

hci_le_big_sync_established_evt()
  bis = hci_conn_hash_lookup_handle(hdev, handle);
  if (!bis)
    bis = hci_conn_add() <- could fail
  /* ... */
  bis = hci_conn_hash_lookup_handle(hdev, handle);
  set_bit(HCI_CONN_BIG_SYNC_FAILED, &bis->flags); <- null-ptr-deref

There is a missing check after hci_conn_hash_lookup_handle(), which can
return NULL. Especially, if a prior hci_conn_add() fails than
hci_conn_hash_lookup_handle() will return NULL.

This patch fixes this by adding a check.

Thanks,
Sungwoo.

Signed-off-by: Sungwoo Kim <iam@sung-woo.kim>
---
 net/bluetooth/hci_event.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 4a27e4a17..d72d238c1 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -7037,6 +7037,8 @@ static void hci_le_big_sync_established_evt(struct hci_dev *hdev, void *data,
 			u16 handle = le16_to_cpu(ev->bis[i]);
 
 			bis = hci_conn_hash_lookup_handle(hdev, handle);
+			if (!bis)
+				continue;
 
 			set_bit(HCI_CONN_BIG_SYNC_FAILED, &bis->flags);
 			hci_connect_cfm(bis, ev->status);
-- 
2.34.1

Re: [PATCH] Bluetooth: HCI: Fix potential null-ptr-deref

Posted by Luiz Augusto von Dentz 1 year, 7 months ago

Hi Sungwoo,

On Wed, May 1, 2024 at 10:22 PM Sungwoo Kim <iam@sung-woo.kim> wrote:
>
> Dear all,

Not sure if you are following what I actually enter as patch
description, that normally doesn't include things like Dear all, etc.

> hci_le_big_sync_established_evt() has a potential null-ptr-deref bug.
>
> hci_le_big_sync_established_evt()
>   bis = hci_conn_hash_lookup_handle(hdev, handle);
>   if (!bis)
>     bis = hci_conn_add() <- could fail
>   /* ... */
>   bis = hci_conn_hash_lookup_handle(hdev, handle);
>   set_bit(HCI_CONN_BIG_SYNC_FAILED, &bis->flags); <- null-ptr-deref
>
> There is a missing check after hci_conn_hash_lookup_handle(), which can
> return NULL. Especially, if a prior hci_conn_add() fails than
> hci_conn_hash_lookup_handle() will return NULL.
>
> This patch fixes this by adding a check.

Nor the one below.

> Thanks,
> Sungwoo.

And by now I'd expect you to start adding the Fixes tag as well.

> Signed-off-by: Sungwoo Kim <iam@sung-woo.kim>
> ---
>  net/bluetooth/hci_event.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
> index 4a27e4a17..d72d238c1 100644
> --- a/net/bluetooth/hci_event.c
> +++ b/net/bluetooth/hci_event.c
> @@ -7037,6 +7037,8 @@ static void hci_le_big_sync_established_evt(struct hci_dev *hdev, void *data,
>                         u16 handle = le16_to_cpu(ev->bis[i]);
>
>                         bis = hci_conn_hash_lookup_handle(hdev, handle);
> +                       if (!bis)
> +                               continue;
>
>                         set_bit(HCI_CONN_BIG_SYNC_FAILED, &bis->flags);
>                         hci_connect_cfm(bis, ev->status);
> --
> 2.34.1
>


-- 
Luiz Augusto von Dentz