linux-kernel - Re: [PATCH] macvtap: fix TUNSETSNDBUF values

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Date:	Fri, 18 Sep 2015 13:50:38 +0300
From:	"Michael S. Tsirkin" <mst@...hat.com>
To:	Christian Borntraeger <borntraeger@...ibm.com>
Cc:	linux-kernel@...r.kernel.org,
	"David S. Miller" <davem@...emloft.net>,
	Matthew Rosato <mjrosato@...ux.vnet.ibm.com>,
	Al Viro <viro@...iv.linux.org.uk>,
	Jason Wang <jasowang@...hat.com>,
	David Gibson <david@...son.dropbear.id.au>,
	Greg Kurz <gkurz@...ux.vnet.ibm.com>,
	Vlad Yasevich <vyasevich@...il.com>,
	Justin Cormack <justin@...iabit.com>,
	Herbert Xu <herbert@...dor.apana.org.au>,
	netdev@...r.kernel.org
Subject: Re: [PATCH] macvtap: fix TUNSETSNDBUF values > 64k

On Fri, Sep 18, 2015 at 12:49:07PM +0200, Christian Borntraeger wrote:
> Am 18.09.2015 um 12:41 schrieb Michael S. Tsirkin:
> > Upon TUNSETSNDBUF,  macvtap reads the requested sndbuf size into
> > a local variable u.
> > commit 39ec7de7092b ("macvtap: fix uninitialized access on
> > TUNSETIFF") changed its type to u16 (which is the right thing to
> > do for all other macvtap ioctls), breaking all values > 64k.
> > 
> > The value of TUNSETSNDBUF is actually a signed 32 bit integer, so
> > the right thing to do is to read it into an int.
> > 
> > Cc: David S. Miller <davem@...emloft.net>
> > Fixes: 39ec7de7092b ("macvtap: fix uninitialized access on TUNSETIFF")
> > Reported-by: Mark A. Peloquin
> > Bisected-by: Matthew Rosato <mjrosato@...ux.vnet.ibm.com>
> > Reported-by: Christian Borntraeger <borntraeger@...ibm.com>
> > Signed-off-by: Michael S. Tsirkin <mst@...hat.com>
> 
> You can add
> Tested-by:  Matthew Rosato <mjrosato@...ux.vnet.ibm.com>
> as this looks identical to an early version of my patch which was tested,
> by Matt. (I send you the other version that changes back u as I felt that
> u and up are named to identify unsigned)
> 
> and please add
> Acked-by: Christian Borntraeger <borntraeger@...ibm.com>
> 
> what about
> CC: stable@...r.kernel.org
> 
> Christian

David Miller adds that himself for netdev patches.

> > ---
> > 
> > This patch probably makes sense on stable.
> > 
> >  drivers/net/macvtap.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
> > index edd7734..248478c 100644
> > --- a/drivers/net/macvtap.c
> > +++ b/drivers/net/macvtap.c
> > @@ -1111,10 +1111,10 @@ static long macvtap_ioctl(struct file *file, unsigned int cmd,
> >  		return 0;
> > 
> >  	case TUNSETSNDBUF:
> > -		if (get_user(u, up))
> > +		if (get_user(s, sp))
> >  			return -EFAULT;
> > 
> > -		q->sk.sk_sndbuf = u;
> > +		q->sk.sk_sndbuf = s;
> >  		return 0;
> > 
> >  	case TUNGETVNETHDRSZ:
> > 
--
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