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

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Message-ID: <CABBYNZLcfQ-sQ8+=5hebVsXC9qZp+Akq-V4SY0hL4FukfwEaQw@mail.gmail.com>
Date: Thu, 2 May 2024 10:48:13 -0400
From: Luiz Augusto von Dentz <luiz.dentz@...il.com>
To: Sungwoo Kim <iam@...g-woo.kim>
Cc: daveti@...due.edu, benquike@...il.com, 
	Marcel Holtmann <marcel@...tmann.org>, Johan Hedberg <johan.hedberg@...il.com>, 
	linux-bluetooth@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Bluetooth: HCI: Fix potential null-ptr-deref

Hi Sungwoo,

On Wed, May 1, 2024 at 10:22 PM Sungwoo Kim <iam@...g-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@...g-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