linux-kernel - Re: BUG FIX: [PATCH RFC v3] memstick_check() memleak in kernel 6.1.0+ introduced pre 4.17

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Date:   Sat, 1 Apr 2023 08:33:36 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Mirsad Goran Todorovac <mirsad.todorovac@....unizg.hr>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Thorsten Leemhuis <regressions@...mhuis.info>,
        Maxim Levitsky <maximlevitsky@...il.com>,
        Alex Dubov <oakad@...oo.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Jens Axboe <axboe@...nel.dk>,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        Hannes Reinecke <hare@...e.de>,
        Jiasheng Jiang <jiasheng@...as.ac.cn>,
        ye xingchen <ye.xingchen@....com.cn>, linux-mmc@...r.kernel.org
Subject: Re: BUG FIX: [PATCH RFC v3] memstick_check() memleak in kernel
 6.1.0+ introduced pre 4.17

On Sat, Apr 01, 2023 at 08:28:07AM +0200, Greg KH wrote:
> On Sat, Apr 01, 2023 at 08:23:26AM +0200, Mirsad Goran Todorovac wrote:
> > > This patch is implying that anyone who calls "dev_set_name()" also has
> > > to do this hack, which shouldn't be the case at all.
> > > 
> > > thanks,
> > > 
> > > greg k-h
> > 
> > This is my best guess. Unless there is dev_free_name() or kobject_free_name(), I don't
> > see a more sensible way to patch this up.
> 
> In sleeping on this, I think this has to move to the driver core.  I
> don't understand why we haven't seen this before, except maybe no one
> has really noticed before (i.e. we haven't had good leak detection tools
> that run with removable devices?)
> 
> Anyway, let me see if I can come up with something this weekend, give me
> a chance...

Wait, no, this already should be handled by the kobject core, look at
kobject_cleanup(), at the bottom.  So your change should be merely
duplicating the logic there that already runs when the struct device is
freed, right?

So I don't understand why your change works, odd.  I need more coffee...

thanks,

greg k-h