linux-kernel - Re: [PATCH] Bluetooth: hci_core: remove acl hdr handle error message

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Message-ID: <CABBYNZJeFv3a=WuKpN0=6KwvELtWXOoRn9HrGhxnVVg_TVaa-Q@mail.gmail.com>
Date: Tue, 8 Oct 2024 10:30:22 -0400
From: Luiz Augusto von Dentz <luiz.dentz@...il.com>
To: Edward Adam Davis <eadavis@...com>
Cc: syzbot+6ea290ba76d8c1eb1ac2@...kaller.appspotmail.com, 
	johan.hedberg@...il.com, linux-bluetooth@...r.kernel.org, 
	linux-kernel@...r.kernel.org, marcel@...tmann.org, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [PATCH] Bluetooth: hci_core: remove acl hdr handle error message

On Tue, Oct 8, 2024 at 10:12 AM Luiz Augusto von Dentz
<luiz.dentz@...il.com> wrote:
>
> Hi Edward,
>
> On Tue, Oct 8, 2024 at 6:47 AM Edward Adam Davis <eadavis@...com> wrote:
> >
> > Syzbot reported a uninit-value in hci_rx_work.This is because l2cap didn't
> > execute the corresponding connection request to call l2cap_send_cmd() or
> > l2cap_do_send(), and ultimately called hci_add_acl_hdr() to set hdr->handle.
>
> What are you talking about here, what these functions have to do with
> a local handle variable?
>
> > Therefore, when calling the thread callback function hci_rx_work() to call
> > hci_acldata_packet, hdr->handle should not be used directly.
>
> It is not being used directly, the handle is a local variable which
> get assigned:
>
>     handle = __le16_to_cpu(hdr->handle);
>
> If what you are saying is that there is no guarantee that skb->len >=
> HCI_ACL_HDR_SIZE then we probably want to replace skb_pull with
> skb_pull_data.
>
> > Reported-and-tested-by: syzbot+6ea290ba76d8c1eb1ac2@...kaller.appspotmail.com
> > Closes: https://syzkaller.appspot.com/bug?extid=6ea290ba76d8c1eb1ac2
> > Signed-off-by: Edward Adam Davis <eadavis@...com>
> > ---
> >  net/bluetooth/hci_core.c | 3 +--
> >  1 file changed, 1 insertion(+), 2 deletions(-)
> >
> > diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
> > index d6976db02c06..20605a7f3f4e 100644
> > --- a/net/bluetooth/hci_core.c
> > +++ b/net/bluetooth/hci_core.c
> > @@ -3791,8 +3791,7 @@ static void hci_acldata_packet(struct hci_dev *hdev, struct sk_buff *skb)
> >                 l2cap_recv_acldata(conn, skb, flags);
> >                 return;
> >         } else {
> > -               bt_dev_err(hdev, "ACL packet for unknown connection handle %d",
> > -                          handle);
> > +               bt_dev_err(hdev, "ACL packet for unknown connection handle");
> >         }
> >
> >         kfree_skb(skb);
> > --
> > 2.43.0
> >
>
>
> --
> Luiz Augusto von Dentz

#syz test

-- 
Luiz Augusto von Dentz

View attachment "v1-0001-Bluetooth-hci_core-Fix-not-checking-skb-length-on.patch" of type "text/x-patch" (1684 bytes)