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Date:   Thu, 6 May 2021 18:00:53 +0300
From:   Pavel Skripkin <paskripkin@gmail.com>
To:     Dan Carpenter <dan.carpenter@oracle.com>
Cc:     Uladzislau Rezki <urezki@gmail.com>, linux-usb@vger.kernel.org,
        linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
        mchehab@kernel.org, syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] WARNING in __vmalloc_node_range
Message-ID: <20210506180053.4770f495@gmail.com>
In-Reply-To: <20210506145722.GC1955@kadam>
References: <000000000000fdc0be05c1a6d68f@google.com>
        <20210506142210.GA37570@pc638.lan>
        <20210506145722.GC1955@kadam>
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On Thu, 6 May 2021 17:57:22 +0300
Dan Carpenter <dan.carpenter@oracle.com> wrote:

> On Thu, May 06, 2021 at 04:22:10PM +0200, Uladzislau Rezki wrote:
> > Seems like vmalloc() is called with zero size passed:
> > 
> > <snip>
> > void *__vmalloc_node_range(unsigned long size, unsigned long align,
> > 			unsigned long start, unsigned long end,
> > gfp_t gfp_mask, pgprot_t prot, unsigned long vm_flags, int node,
> > 			const void *caller)
> > {
> > 	struct vm_struct *area;
> > 	void *addr;
> > 	unsigned long real_size = size;
> > 	unsigned long real_align = align;
> > 	unsigned int shift = PAGE_SHIFT;
> > 
> > 2873	if (WARN_ON_ONCE(!size))
> > 		return NULL;
> > <snip>
> > 
> > from the dvb_dmx_init() driver:
> > 
> > <snip>
> > int dvb_dmx_init(struct dvb_demux *dvbdemux)
> > {
> > 	int i;
> > 	struct dmx_demux *dmx = &dvbdemux->dmx;
> > 
> > 	dvbdemux->cnt_storage = NULL;
> > 	dvbdemux->users = 0;
> > 1251	dvbdemux->filter = vmalloc(array_size(sizeof(struct
> > dvb_demux_filter), <snip>
> >    dvbdemux->filternum));
> 
> Indeed.
> 
> It is a mystery because array_size() should never return less than
> sizeof(struct dvb_demux_filter).  That's the whole point of the
> array_size() function is that it returns ULONG_MAX if there is an
> integer overflow.
> 
> regards,
> dan carpenter
> 
> 
> 

Hi!

I've already sent the patch:
https://patchwork.linuxtv.org/project/linux-media/patch/20210506121211.8556-1-paskripkin@gmail.com/


With regards,
Pavel Skripkin