From: Andrew Morton <akpm@linux-foundation.org>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: syzbot <syzbot+882a85c0c8ec4a3e2281@syzkaller.appspotmail.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
syzkaller-bugs@googlegroups.com,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-usb@vger.kernel.org
Subject: Re: [syzbot] WARNING in do_proc_bulk
Date: Mon, 3 May 2021 12:24:28 -0700 [thread overview]
Message-ID: <20210503122428.30ebfddbaf8f5184dc73e1a7@linux-foundation.org> (raw)
In-Reply-To: <20210503185614.GA628313@rowland.harvard.edu>
On Mon, 3 May 2021 14:56:14 -0400 Alan Stern <stern@rowland.harvard.edu> wrote:
> >
> > do_proc_bulk() is asking kmalloc for more than MAX_ORDER bytes, in
> >
> > tbuf = kmalloc(len1, GFP_KERNEL);
>
> This doesn't seem to be a bug. do_proc_bulk is simply trying to
> allocate a kernel buffer for data passed to/from userspace. If a user
> wants too much space all at once, that's their problem.
>
> As far as I know, the kmalloc API doesn't require the caller to filter
> out requests for more the MAX_ORDER bytes. Only to be prepared to
> handle failures -- which do_proc_bulk is all set for.
>
> Am I wrong about this? Should we add __GFP_NOWARN to the gfp flags?
Yes, if the oversized request is a can-happen and the resulting error is handled
appropriately, __GFP_NOWARN is the way to go.
next prev parent reply other threads:[~2021-05-03 19:24 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-02 20:00 [syzbot] WARNING in do_proc_bulk syzbot
2021-05-02 20:00 ` syzbot
2021-05-03 10:25 ` syzbot
2021-05-03 10:25 ` syzbot
2021-05-03 17:53 ` Andrew Morton
2021-05-03 18:56 ` Alan Stern
2021-05-03 19:24 ` Andrew Morton [this message]
2021-05-04 0:47 ` Alan Stern
2021-05-04 1:07 ` syzbot
2021-05-04 1:07 ` syzbot
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