From: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
To: syzbot <syzbot+d55757faa9b80590767b@syzkaller.appspotmail.com>,
syzkaller-bugs@googlegroups.com
Cc: dhowells@redhat.com, christophe.jaillet@wanadoo.fr,
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com,
David Howells <dhowells@redhat.com>
Subject: Re: [syzbot] KASAN: null-ptr-deref Read in __free_pages
Date: Mon, 21 Mar 2022 09:50:05 +0100 [thread overview]
Message-ID: <1905446.yKVeVyVuyW@leap> (raw)
In-Reply-To: <970502.1647851062@warthog.procyon.org.uk>
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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>
This way you are doing two test for each iteration of the loop that calls
__free_pages(). One for the index "i" to stay less that an unnecessary
high limit, the other for pages[i] being NULL.
However, since you are the Maintainer, yours are the rules :)
Regards,
Fabio M. De Francesco
next prev parent reply other threads:[~2022-03-21 8:50 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-20 22:04 [syzbot] KASAN: null-ptr-deref Read in __free_pages syzbot
2022-03-20 23:32 ` Fabio M. De Francesco
2022-03-20 23:38 ` syzbot
2022-03-20 23:40 ` Fabio M. De Francesco
2022-03-20 23:50 ` syzbot
2022-03-21 0:28 ` Fabio M. De Francesco
2022-03-21 0:37 ` syzbot
2022-03-21 8:46 ` David Howells
2022-03-21 9:02 ` Fabio M. De Francesco
2022-03-21 9:37 ` David Howells
2022-03-21 8:24 ` David Howells
2022-03-21 8:34 ` syzbot
2022-03-21 8:43 ` Fabio M. De Francesco
2022-03-21 8:50 ` Fabio M. De Francesco [this message]
2022-03-21 11:19 ` David Howells
2022-03-21 11:30 ` syzbot
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