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From: Mathias Nyman <mathias.nyman@linux.intel.com>
To: Jia-Ju Bai <baijiaju@buaa.edu.cn>,
	mathias.nyman@intel.com, gregkh@linuxfoundation.org,
	p.zabel@pengutronix.de
Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] usb: host: xhci: Add a NULL check of hcd in xhci_plat_remove()
Date: Thu, 23 Mar 2023 14:51:38 +0200	[thread overview]
Message-ID: <80f92044-6f3d-cdd8-a7d4-8793927a648b@linux.intel.com> (raw)
In-Reply-To: <20230323081329.366459-1-baijiaju@buaa.edu.cn>

On 23.3.2023 10.13, Jia-Ju Bai wrote:
> In a previous commit d7de14d74d65 ("usb: xhci_plat_remove: avoid NULL
> dereference"), hcd can be NULL in usb_remove_hcd(), and thus it should
> be checked before being used.

hcd shouldn't be null in usb_remove_hcd()
That was a bug which was properly fixed shortly after in:

4a593a62a9e3 xhci: Fix null pointer dereference in remove if xHC has only one roothub

I guess commit d7de14d74d65 ("usb: xhci_plat_remove: avoid NULL dereference") Isn't really
needed either anymore, but no harm in keeping it.

> 
> However, in the call stack of this commit, hci is also used to get xhci:
> > xhci_plat_remove()
>    xhci = hcd_to_xhci(hcd)
>      usb_hcd_is_primary_hcd(hcd)
>        if (!hcd->primary_hcd) -> No check for hcd
>      primary_hcd = hcd->primary_hcd; -> No check for hcd
>    usb_remove_hcd(hcd)
>      if (!hcd) -> Add a check by the previous commit

These hcd checks shouldn't be needed.

Thanks
Mathias

      reply	other threads:[~2023-03-23 12:50 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-03-23  8:13 Jia-Ju Bai
2023-03-23 12:51 ` Mathias Nyman [this message]

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