netdev - Re: [PATCH] rtlwifi: Fix null-pointer dereferences in error handling code of rtl_pci

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Message-ID: <87pno24tev.fsf@kamboji.qca.qualcomm.com>
Date:   Tue, 28 May 2019 16:09:44 +0300
From:   Kalle Valo <kvalo@...eaurora.org>
To:     Larry Finger <Larry.Finger@...inger.net>
Cc:     Jia-Ju Bai <baijiaju1990@...il.com>, pkshih@...ltek.com,
        davem@...emloft.net, linux-wireless@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] rtlwifi: Fix null-pointer dereferences in error handling code of rtl_pci_probe()

Larry Finger <Larry.Finger@...inger.net> writes:

> On 5/28/19 6:55 AM, Kalle Valo wrote:
>> Jia-Ju Bai <baijiaju1990@...il.com> wrote:
>>
>>> *BUG 1:
>>> In rtl_pci_probe(), when rtlpriv->cfg->ops->init_sw_vars() fails,
>>> rtl_deinit_core() in the error handling code is executed.
>>> rtl_deinit_core() calls rtl_free_entries_from_scan_list(), which uses
>>> rtlpriv->scan_list.list in list_for_each_entry_safe(), but it has been
>>> initialized. Thus a null-pointer dereference occurs.
>>> The reason is that rtlpriv->scan_list.list is initialized by
>>> INIT_LIST_HEAD() in rtl_init_core(), which has not been called.
>>>
>>> To fix this bug, rtl_deinit_core() should not be called when
>>> rtlpriv->cfg->ops->init_sw_vars() fails.
>>>
>>> *BUG 2:
>>> In rtl_pci_probe(), rtl_init_core() can fail when rtl_regd_init() in
>>> this function fails, and rtlpriv->scan_list.list has not been
>>> initialized by INIT_LIST_HEAD(). Then, rtl_deinit_core() in the error
>>> handling code of rtl_pci_probe() is executed. Finally, a null-pointer
>>> dereference occurs due to the same reason of the above bug.
>>>
>>> To fix this bug, the initialization of lists in rtl_init_core() are
>>> performed before the call to rtl_regd_init().
>>>
>>> These bugs are found by a runtime fuzzing tool named FIZZER written by
>>> us.
>>>
>>> Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>
>>
>> Ping & Larry, is this ok to take?
>>
>
> Kalle,
>
> Not at the moment. In reviewing the code, I was unable to see how this
> situation could develop, and his backtrace did not mention any rtlwifi
> code. For that reason, I asked him to add printk stat4ements to show
> the last part of rtl_pci that executed correctly. In
> https://marc.info/?l=linux-wireless&m=155788322631134&w=2, he promised
> to do that, but I have not seen the result.

Ok, thanks. I'll then drop this, please resubmit once everything is
understood and the patch is ready to be applied.

-- 
Kalle Valo