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From: Eric Biggers <ebiggers@kernel.org>
To: Anmol Karn <anmol.karan123@gmail.com>
Cc: syzbot+0bef568258653cff272f@syzkaller.appspotmail.com,
	johan.hedberg@gmail.com, netdev@vger.kernel.org,
	marcel@holtmann.org, syzkaller-bugs@googlegroups.com,
	linux-kernel@vger.kernel.org, linux-bluetooth@vger.kernel.org,
	kuba@kernel.org, linux-kernel-mentees@lists.linuxfoundation.org,
	davem@davemloft.net
Subject: Re: [Linux-kernel-mentees] [PATCH] net: bluetooth: Fix null pointer dereference in hci_event_packet()
Date: Wed, 9 Sep 2020 22:06:59 -0700	[thread overview]
Message-ID: <20200910050659.GD828@sol.localdomain> (raw)
In-Reply-To: <20200910043424.19894-1-anmol.karan123@gmail.com>

On Thu, Sep 10, 2020 at 10:04:24AM +0530, Anmol Karn wrote:
> Prevent hci_phy_link_complete_evt() from dereferencing 'hcon->amp_mgr'
> as NULL. Fix it by adding pointer check for it.
> 
> Reported-and-tested-by: syzbot+0bef568258653cff272f@syzkaller.appspotmail.com
> Link: https://syzkaller.appspot.com/bug?extid=0bef568258653cff272f
> Signed-off-by: Anmol Karn <anmol.karan123@gmail.com>
> ---
>  net/bluetooth/hci_event.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
> index 4b7fc430793c..871e16804433 100644
> --- a/net/bluetooth/hci_event.c
> +++ b/net/bluetooth/hci_event.c
> @@ -4936,6 +4936,11 @@ static void hci_phy_link_complete_evt(struct hci_dev *hdev,
>  		return;
>  	}
>  
> +	if (IS_ERR_OR_NULL(hcon->amp_mgr)) {
> +		hci_dev_unlock(hdev);
> +		return;
> +	}
> +

In patches that fix a NULL pointer dereference, please include a brief
explanation of why the pointer can be NULL, including what it means
semantically; and why the proposed change is the best fix for the problem.

Also, why IS_ERR_OR_NULL()?

- Eric
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  reply	other threads:[~2020-09-10  5:07 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-10  4:34 Anmol Karn
2020-09-10  5:06 ` Eric Biggers [this message]
2020-09-10  6:02   ` Anmol Karn
2020-09-10 10:49 ` Dan Carpenter
2020-09-10 14:58   ` Anmol Karn
2020-09-12  9:10   ` Anmol Karn
2020-09-14 15:44     ` Dan Carpenter
2020-09-14 18:37       ` Anmol Karn
2020-09-29 17:32       ` Anmol Karn
2020-09-30 14:18         ` Anmol Karn
2020-10-01  7:06           ` Marcel Holtmann
2020-10-01  7:45             ` Anmol Karn

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