netdev - Re: [PATCH 1/6] can: esd_usb: Fix possible calls to kfree() with NULL

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Message-ID: <cbd6a3785645a6740de2e7e09b07e3fdf9392bf6.camel@esd.eu>
Date: Tue, 19 Aug 2025 16:16:17 +0000
From: Stefan Mätje <stefan.maetje@....eu>
To: "mkl@...gutronix.de" <mkl@...gutronix.de>
CC: "mailhol@...nel.org" <mailhol@...nel.org>, "socketcan@...tkopp.net"
	<socketcan@...tkopp.net>, "linux-can@...r.kernel.org"
	<linux-can@...r.kernel.org>, socketcan <socketcan@....eu>, Frank Jungclaus
	<frank.jungclaus@....eu>, "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"horms@...nel.org" <horms@...nel.org>, "olivier@...rie.be"
	<olivier@...rie.be>
Subject: Re: [PATCH 1/6] can: esd_usb: Fix possible calls to kfree() with NULL

Am Freitag, dem 15.08.2025 um 15:02 +0000 schrieb Stefan Mätje:
> Am Mittwoch, dem 13.08.2025 um 11:20 +0200 schrieb Marc Kleine-Budde:
> > On 11.08.2025 23:06:06, Stefan Mätje wrote:
> > > In esd_usb_start() kfree() is called with the msg variable even if the
> > > allocation of *msg failed.
> > > 
> > > Move the kfree() call to a line before the allocation error exit label
> > > out: and adjust the exits for other errors to the new free_msg: label
> > > just before kfree().
> > > 
> > > In esd_usb_probe() add free_dev: label and skip calling kfree() if
> > > allocation of *msg failed.
> > > 
> > > Fixes: fae37f81fdf3 ( "net: can: esd_usb2: Do not do dma on the stack" )
> > > Signed-off-by: Stefan Mätje <stefan.maetje@....eu>
> > > ---
> > >  drivers/net/can/usb/esd_usb.c | 16 +++++++++-------
> > >  1 file changed, 9 insertions(+), 7 deletions(-)
> > > 
> > > diff --git a/drivers/net/can/usb/esd_usb.c b/drivers/net/can/usb/esd_usb.c
> > > index 27a3818885c2..05ed664cf59d 100644
> > > --- a/drivers/net/can/usb/esd_usb.c
> > > +++ b/drivers/net/can/usb/esd_usb.c
> > > @@ -3,7 +3,7 @@
> > >   * CAN driver for esd electronics gmbh CAN-USB/2, CAN-USB/3 and CAN-USB/Micro
> > >   *
> > >   * Copyright (C) 2010-2012 esd electronic system design gmbh, Matthias Fuchs <socketcan@....eu>
> > > - * Copyright (C) 2022-2024 esd electronics gmbh, Frank Jungclaus <frank.jungclaus@....eu>
> > > + * Copyright (C) 2022-2025 esd electronics gmbh, Frank Jungclaus <frank.jungclaus@....eu>
> > >   */
> > >  
> > >  #include <linux/can.h>
> > > @@ -746,21 +746,22 @@ static int esd_usb_start(struct esd_usb_net_priv *priv)
> > 
> > 	msg = kmalloc(sizeof(*msg), GFP_KERNEL);
> > 	if (!msg) {
> > 		err = -ENOMEM;
> > 		goto out;
> > 	}
> > 
> > Can you adjust the jump label for the kmalloc() fail. There's no need to
> > check for -ENODEV
> 
> Yes, I will move it in the next iteration. Thanks for that hint.
> 
Hi Marc,

since there have been some rather rejecting emails, I will withdraw patch 1. 
Therefore, the function esd_usb_start() will remain unchanged in the next
iteration.

Stefan