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([2001:a61:138e:201:27e2:fe9:90b9:6b9a]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a6f1b2f674dsm399315366b.204.2024.06.12.00.43.55 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 12 Jun 2024 00:43:56 -0700 (PDT) Message-ID: Date: Wed, 12 Jun 2024 09:43:55 +0200 Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: USB Denial Of Service To: Alan Stern , Oliver Neukum , Greg KH Cc: USB mailing list References: <40dfa45b-5f21-4eef-a8c1-51a2f320e267@rowland.harvard.edu> Content-Language: en-US From: Oliver Neukum In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 11.06.24 21:09, Alan Stern wrote: > Alternatively, the driver could avoid resubmitting the URB when one of > those errors occurs. This is perhaps less appropriate, because these > kinds of errors can be transient (although that is normally rare). Optimally we'd wait a small delay and resubmit after that for a limited number of attempts. In fact optimally we'd add helpers to do so for all drivers to use. However, to make this wor with suspend, reset and disconnect would take work. Is a corner case worth that? > Index: usb-devel/drivers/usb/class/cdc-wdm.c > =================================================================== > --- usb-devel.orig/drivers/usb/class/cdc-wdm.c > +++ usb-devel/drivers/usb/class/cdc-wdm.c > @@ -266,14 +266,14 @@ static void wdm_int_callback(struct urb > dev_err(&desc->intf->dev, "Stall on int endpoint\n"); > goto sw; /* halt is cleared in work */ > default: > - dev_err(&desc->intf->dev, > + dev_dbg(&desc->intf->dev, Good idea. > "nonzero urb status received: %d\n", status); > break; > } > } > > if (urb->actual_length < sizeof(struct usb_cdc_notification)) { > - dev_err(&desc->intf->dev, "wdm_int_callback - %d bytes\n", > + dev_dbg(&desc->intf->dev, "wdm_int_callback - %d bytes\n", Not so good idea. If that happens it points to either a bug in the firmware or a malicious device. Such things need to be logged. Regards Oliver