Re: [PATCH] net: ieee802154: fix a null pointer in nl802154_trigger_scan

[Miquel Raynal <miquel.raynal@bootlin.com>]

Hi 慕冬亮,

dzm91@hust.edu.cn wrote on Tue, 7 Mar 2023 17:21:49 +0800 (GMT+08:00):

> > -----原始邮件-----
> > 发件人: "Miquel Raynal" <miquel.raynal@bootlin.com>
> > 发送时间: 2023-03-07 17:09:03 (星期二)
> > 收件人: "Denis Kirjanov" <dkirjanov@suse.de>
> > 抄送: "Dongliang Mu" <dzm91@hust.edu.cn>, "Alexander Aring" <alex.aring@gmail.com>, "Stefan Schmidt" <stefan@datenfreihafen.org>, "David
> >  S. Miller" <davem@davemloft.net>, "Eric Dumazet" <edumazet@google.com>, "Jakub
> >  Kicinski" <kuba@kernel.org>, "Paolo Abeni" <pabeni@redhat.com>, syzbot+bd85b31816913a32e473@syzkaller.appspotmail.com, linux-wpan@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org
> > 主题: Re: [PATCH] net: ieee802154: fix a null pointer in nl802154_trigger_scan
> > 
> > Hello,
> > 
> > dkirjanov@suse.de wrote on Tue, 7 Mar 2023 11:43:46 +0300:
> >   
> > > On 3/7/23 10:30, Dongliang Mu wrote:  
> > > > There is a null pointer dereference if NL802154_ATTR_SCAN_TYPE is
> > > > not set by the user.
> > > > 
> > > > Fix this by adding a null pointer check.  
> > 
> > Thanks for the patch! This has been fixed already:
> > https://lore.kernel.org/linux-wpan/20230301154450.547716-1-miquel.raynal@bootlin.com/T/#u  
> 
> Oh, I see. Thanks for your reply.
> 
> A small issue: should we still check !nla_get_u8(info->attrs[NL802154_ATTR_SCAN_TYPE])?

Isn't it already handled? There is a switch case over it with a default
statement to handle unsupported scan types.

> > > > Reported-and-tested-by: syzbot+bd85b31816913a32e473@syzkaller.appspotmail.com  
> > 
> > Just for reference, this tag shall not be used:
> > 
> > 	"Please do not use combined tags, e.g.
> > 	``Reported-and-tested-by``"
> > 	Documentation/process/maintainer-tip.rst
> >   
> 
> Okay. This is suggested by Syzbot. I will use separate tags in the future.
> 
> > > > Signed-off-by: Dongliang Mu <dzm91@hust.edu.cn>    
> > > 
> > > Please add a Fixes: tag 
> > >   
> > > > ---
> > > >  net/ieee802154/nl802154.c | 3 ++-
> > > >  1 file changed, 2 insertions(+), 1 deletion(-)
> > > > 
> > > > diff --git a/net/ieee802154/nl802154.c b/net/ieee802154/nl802154.c
> > > > index 2215f576ee37..1cf00cffd63f 100644
> > > > --- a/net/ieee802154/nl802154.c
> > > > +++ b/net/ieee802154/nl802154.c
> > > > @@ -1412,7 +1412,8 @@ static int nl802154_trigger_scan(struct sk_buff *skb, struct genl_info *info)
> > > >  		return -EOPNOTSUPP;
> > > >  	}
> > > >  
> > > > -	if (!nla_get_u8(info->attrs[NL802154_ATTR_SCAN_TYPE])) {
> > > > +	if (!info->attrs[NL802154_ATTR_SCAN_TYPE] ||
> > > > +	    !nla_get_u8(info->attrs[NL802154_ATTR_SCAN_TYPE])) {
> > > >  		NL_SET_ERR_MSG(info->extack, "Malformed request, missing scan type");
> > > >  		return -EINVAL;
> > > >  	}    
> > 
> > 
> > Thanks,
> > Miquèl  
> 
> 
> --
> Best regards,
> Dongliang Mu


Thanks,
Miquèl