| Subject | Re: [PATCH 4.4 60/74] ipv6: fix udpv6 sendmsg crash caused by too small MTU | From | Ben Hutchings <> | Date | Mon, 19 Feb 2018 20:46:13 +0100 |
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On Mon, 2018-01-29 at 13:57 +0100, Greg Kroah-Hartman wrote: > 4.4-stable review patch. If anyone has any objections, please let me know. > > ------------------ > > From: Mike Maloney <maloney@google.com> > > > [ Upstream commit 749439bfac6e1a2932c582e2699f91d329658196 ] [...] > --- a/net/ipv6/ip6_output.c > +++ b/net/ipv6/ip6_output.c > @@ -1246,14 +1246,16 @@ static int ip6_setup_cork(struct sock *s > v6_cork->tclass = tclass; > if (rt->dst.flags & DST_XFRM_TUNNEL) > mtu = np->pmtudisc >= IPV6_PMTUDISC_PROBE ? > - rt->dst.dev->mtu : dst_mtu(&rt->dst); > + READ_ONCE(rt->dst.dev->mtu) : dst_mtu(&rt->dst); > else > mtu = np->pmtudisc >= IPV6_PMTUDISC_PROBE ? > - rt->dst.dev->mtu : dst_mtu(rt->dst.path); > + READ_ONCE(rt->dst.dev->mtu) : dst_mtu(rt->dst.path); > if (np->frag_size < mtu) { > if (np->frag_size) > mtu = np->frag_size; > } > + if (mtu < IPV6_MIN_MTU) > + return -EINVAL;
This error path appears to leak a reference to rt->dst.
Ben.
> cork->base.fragsize = mtu; > if (dst_allfrag(rt->dst.path)) > cork->base.flags |= IPCORK_ALLFRAG; > > > -- Ben Hutchings Software Developer, Codethink Ltd.
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