linux-kernel - Re: [syzbot] KASAN: null-ptr-deref Read in __free

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Message-ID: <2113719.Icojqenx9y@leap>
Date:   Mon, 21 Mar 2022 09:43:58 +0100
From:   "Fabio M. De Francesco" <fmdefrancesco@...il.com>
To:     syzbot <syzbot+d55757faa9b80590767b@...kaller.appspotmail.com>,
        syzkaller-bugs@...glegroups.com,
        David Howells <dhowells@...hat.com>
Cc:     dhowells@...hat.com, christophe.jaillet@...adoo.fr,
        linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] KASAN: null-ptr-deref Read in __free_pages

On lunedì 21 marzo 2022 09:24:22 CET David Howells wrote:
> It should be possible to just test for the pointer being NULL in the loop
> before calling __free_pages() since the list was allocated with kcalloc().
> 
> David
> 
> #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git 6d39b096627f0a1eb6e14f049d8ae3c93e0290f2
> 
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> 
Hello David,

I had already sent a patch for this problem:
https://lore.kernel.org/lkml/20220321014246.19941-1-fmdefrancesco@gmail.com/

However, I see that you ignored mine and preferred yours. I would have appreciated 
to have your review of my patch or to discuss the pros and cons of yours vs. my 
solution and be CC'ed in this thread because I've spent some time on it :)

Best regards,

Fabio M. De Francesco