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Mon, 20 Nov 2023 02:45:07 -0800 (PST) Received: from [192.168.1.20] ([178.197.222.11]) by smtp.gmail.com with ESMTPSA id lz10-20020a170906fb0a00b009737b8d47b6sm3732334ejb.203.2023.11.20.02.45.06 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 20 Nov 2023 02:45:07 -0800 (PST) Message-ID: Date: Mon, 20 Nov 2023 11:45:05 +0100 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] nfc: virtual_ncidev: Add variable to check if ndev is running Content-Language: en-US To: Nguyen Dinh Phi , bongsu.jeon@samsung.com Cc: "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "syzbot+6eb09d75211863f15e3e@syzkaller.appspotmail.com" References: <20231119164705.1991375-1-phind.uet@gmail.com> <20231120044706epcms2p48c4579db14cc4f3274031036caac4718@epcms2p4> <20d93e83-66c0-28d9-4426-a0d4c098f303@gmail.com> From: Krzysztof Kozlowski Autocrypt: addr=krzysztof.kozlowski@linaro.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 20/11/2023 11:39, Nguyen Dinh Phi wrote: >>>> mutex_lock(&vdev->mtx); >>>> kfree_skb(vdev->send_buff); >>>> vdev->send_buff = NULL; >>>> + vdev->running = false; >>>> mutex_unlock(&vdev->mtx); >>>> >>>> return 0; >>>> @@ -50,7 +55,7 @@ static int virtual_nci_send(struct nci_dev *ndev, struct sk_buff *skb) >>>> struct virtual_nci_dev *vdev = nci_get_drvdata(ndev); >>>> >>>> mutex_lock(&vdev->mtx); >>>> - if (vdev->send_buff) { >>>> + if (vdev->send_buff || !vdev->running) { >>> >>> Dear Krzysztof, >>> >>> I agree this defensive code. >>> But i think NFC submodule has to avoid this situation.(calling send function of closed nci_dev) >>> Could you check this? >> >> This code looks not effective. At this point vdev->send_buff is always >> false, so the additional check would not bring any value. >> >> I don't see this fixing anything. Syzbot also does not seem to agree. >> >> Nguyen, please test your patches against syzbot *before* sending them. >> If you claim this fixes the report, please provide me the link to syzbot >> test results confirming it is fixed. >> >> I looked at syzbot dashboard and do not see this issue fixed with this >> patch. >> >> Best regards, >> Krzysztof >> > > Hi Krzysztof, > > I've submitted it to syzbot, it is the test request that created at > [2023/11/20 09:39] in dashboard link > https://syzkaller.appspot.com/bug?extid=6eb09d75211863f15e3e ...and I see there two errors. I don't know, maybe I miss something obvious (our brains like to do it sometimes), but please explain me how this could fix anything? Best regards, Krzysztof