linux-kernel - Re: [PATCH] bluetooth/virtio_bt: Fix dereference null return value

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Message-Id: <EE77EBBE-EB8A-475D-A1DA-BC35DD14B3E0@holtmann.org>
Date:   Sun, 4 Jul 2021 19:33:10 +0200
From:   Marcel Holtmann <marcel@...tmann.org>
To:     John Wood <john.wood@....com>
Cc:     Johan Hedberg <johan.hedberg@...il.com>,
        Luiz Augusto von Dentz <luiz.dentz@...il.com>,
        stable <stable@...r.kernel.org>,
        Bluetooth Kernel Mailing List 
        <linux-bluetooth@...r.kernel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] bluetooth/virtio_bt: Fix dereference null return value

Hi John,

> The alloc_skb function returns NULL on error. So, test this case and
> avoid a NULL dereference (skb->data).
> 
> Addresses-Coverity-ID: 1484718 ("Dereference null return value")
> Fixes: afd2daa26c7ab ("Bluetooth: Add support for virtio transport driver")
> Signed-off-by: John Wood <john.wood@....com>
> ---
> drivers/bluetooth/virtio_bt.c | 2 ++
> 1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/bluetooth/virtio_bt.c b/drivers/bluetooth/virtio_bt.c
> index c804db7e90f8..5f82574236c0 100644
> --- a/drivers/bluetooth/virtio_bt.c
> +++ b/drivers/bluetooth/virtio_bt.c
> @@ -34,6 +34,8 @@ static int virtbt_add_inbuf(struct virtio_bluetooth *vbt)
> 	int err;
> 
> 	skb = alloc_skb(1000, GFP_KERNEL);
> +	if (!skb)
> +		return -ENOMEM;
> 	sg_init_one(sg, skb->data, 1000);

this is already fixed.

Author: Colin Ian King <colin.king@...onical.com>
Date:   Fri Apr 9 17:53:14 2021 +0100

    Bluetooth: virtio_bt: add missing null pointer check on alloc_skb call return
    
    The call to alloc_skb with the GFP_KERNEL flag can return a null sk_buff
    pointer, so add a null check to avoid any null pointer deference issues.
    
    Addresses-Coverity: ("Dereference null return value")
    Fixes: afd2daa26c7a ("Bluetooth: Add support for virtio transport driver")
    Signed-off-by: Colin Ian King <colin.king@...onical.com>
    Signed-off-by: Marcel Holtmann <marcel@...tmann.org>

Regards

Marcel