Linux CAN drivers development
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From: Greg KH <gregkh@linuxfoundation.org>
To: "Dynetrex, Admin" <admin@dynetrex.com>
Cc: linux-can@vger.kernel.org, peter_hong@fintek.com.tw,
	mkl@pengutronix.de, mailhol@kernel.org, stable@kernel.org
Subject: Re: [REGRESSION] can: usb: f81604: TX broken with "short int URB: 9 < 12"
Date: Tue, 7 Jul 2026 07:59:03 +0200	[thread overview]
Message-ID: <2026070732-reformer-civil-a4d8@gregkh> (raw)
In-Reply-To: <A3834A07-5639-4779-844F-C5843DFC3928@dynetrex.com>

On Mon, Jul 06, 2026 at 10:46:00PM -0700, Dynetrex, Admin wrote:
> Hello,
> 
> I found an issue with a patch applied to the can/usb/f81604 driver on 2026-02-23.
> 
> https://git.kernel.org/stable/c/36ead57443146e6b730ce1f48ca3e9b17e19a3d2
> 
> The patch added a check to make sure urb->actual_length is not less than sizeof(struct f81604_int_data). The issue is that the interrupt data from the device is 9 bytes, but sizeof(struct f81604_int_data) returns 12 because the struct is marked __aligned(4).
> 
> This causes valid interrupt URBs to be rejected. After this patch, CAN frames no longer transmit successfully, while before the patch they transmitted without issue.
> 
> Each transmit attempt logs the following in dmesg:
> 
> f81604_read_int_callback: short int URB: 9 < 12
> 
> Please consider either removing the __aligned(4) attribute from struct f81604_int_data, or using a constant for the actual wire packet length when checking urb->actual_length.

Please consider submitting a patch to resolve this issue so you get full
credit for the fix.

thanks,

greg k-h

      reply	other threads:[~2026-07-07  5:58 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-07-07  5:46 [REGRESSION] can: usb: f81604: TX broken with "short int URB: 9 < 12" Dynetrex, Admin
2026-07-07  5:59 ` Greg KH [this message]

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