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From: Sascha Hauer <s.hauer@pengutronix.de>
To: Antony Pavlov <antonynpavlov@gmail.com>
Cc: barebox@lists.infradead.org, Oleksij Rempel <o.rempel@pengutronix.de>
Subject: Re: [RFC] sandbox: prevent segfault in tap_alloc()
Date: Fri, 28 Jun 2019 11:04:30 +0200	[thread overview]
Message-ID: <20190628090430.jjpxyr6a7skn76ae@pengutronix.de> (raw)
In-Reply-To: <20190628113226.fb03528ce02c085c039006f4@gmail.com>

On Fri, Jun 28, 2019 at 11:32:26AM +0300, Antony Pavlov wrote:
> On Wed, 26 Jun 2019 09:12:02 +0200
> Sascha Hauer <s.hauer@pengutronix.de> wrote:
> 
> > Hi Antony,
> > 
> > On Wed, Jun 19, 2019 at 01:49:16PM +0300, Antony Pavlov wrote:
> > > Tap network interface initialization in sandbox
> > > barebox leads to segfault under Debian Buster/Sid.
> > > 
> > > The problem is that strcpy(dev, ifr.ifr_name) inside
> > > tap_alloc() tries to alter read-only data passed
> > > by tap_probe() and barebox receives SIGSEGV.
> > > 
> > > Signed-off-by: Antony Pavlov <antonynpavlov@gmail.com>
> > > ---
> > >  drivers/net/tap.c | 4 ++--
> > >  1 file changed, 2 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/drivers/net/tap.c b/drivers/net/tap.c
> > > index 1fbfa085b1..d7e32f4875 100644
> > > --- a/drivers/net/tap.c
> > > +++ b/drivers/net/tap.c
> > > @@ -14,7 +14,7 @@
> > >  
> > >  struct tap_priv {
> > >  	int fd;
> > > -	char *name;
> > > +	char name[128];
> > >  };
> > >  
> > >  static int tap_eth_send(struct eth_device *edev, void *packet, int length)
> > > @@ -65,7 +65,7 @@ static int tap_probe(struct device_d *dev)
> > >  	int ret = 0;
> > >  
> > >  	priv = xzalloc(sizeof(struct tap_priv));
> > > -	priv->name = "barebox";
> > > +	strncpy(priv->name, "barebox", sizeof(priv->name));
> > >  
> > >  	priv->fd = tap_alloc(priv->name);
> > 
> > Can we change the prototype of tap_alloc() to something like this:
> > 
> > int tap_alloc(const char *name, int *fd, char **outname);
> > 
> > outname would be an allocated string to be freed by the caller.
> 
> There is one problem.
> tap_alloc works in the sandbox "os domain" (glibc *alloc&free etc),
> the caller works in the "barebox domain" (barebox *alloc&free).

Oh, I didn't realize this.

> 
> Can we just drop this outname?
> nobody actually use it at the moment.

Yes, let's just drop it.

Sascha


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      reply	other threads:[~2019-06-28  9:04 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-19 10:49 Antony Pavlov
2019-06-26  7:12 ` Sascha Hauer
2019-06-28  8:32   ` Antony Pavlov
2019-06-28  9:04     ` Sascha Hauer [this message]

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