Messages in this thread | | | From | Kuniyuki Iwashima <> | Subject | Re: [PATCH v2 net 2/5] udp: Call inet6_destroy_sock() in setsockopt(IPV6_ADDRFORM). | Date | Tue, 27 Sep 2022 22:29:05 -0700 |
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From: Eric Dumazet <edumazet@google.com> Date: Tue, 27 Sep 2022 22:05:09 -0700 > On Tue, Sep 27, 2022 at 5:28 PM Kuniyuki Iwashima <kuniyu@amazon.com> wrote: > > > > Commit 4b340ae20d0e ("IPv6: Complete IPV6_DONTFRAG support") forgot > > to add a change to free inet6_sk(sk)->rxpmtu while converting an IPv6 > > socket into IPv4 with IPV6_ADDRFORM. After conversion, sk_prot is > > changed to udp_prot and ->destroy() never cleans it up, resulting in > > a memory leak. > > > > This is due to the discrepancy between inet6_destroy_sock() and > > IPV6_ADDRFORM, so let's call inet6_destroy_sock() from IPV6_ADDRFORM > > to remove the difference. > > > > However, this is not enough for now because rxpmtu can be changed > > without lock_sock() after commit 03485f2adcde ("udpv6: Add lockless > > sendmsg() support"). We will fix this case in the following patch. > > > > Fixes: 4b340ae20d0e ("IPv6: Complete IPV6_DONTFRAG support") > > Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> > > --- > > net/ipv6/ipv6_sockglue.c | 15 +++------------ > > 1 file changed, 3 insertions(+), 12 deletions(-) > > > > diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c > > index b61066ac8648..030a4cf23ceb 100644 > > --- a/net/ipv6/ipv6_sockglue.c > > +++ b/net/ipv6/ipv6_sockglue.c > > @@ -431,9 +431,6 @@ static int do_ipv6_setsockopt(struct sock *sk, int level, int optname, > > if (optlen < sizeof(int)) > > goto e_inval; > > if (val == PF_INET) { > > - struct ipv6_txoptions *opt; > > - struct sk_buff *pktopt; > > - > > if (sk->sk_type == SOCK_RAW) > > break; > > > > @@ -464,7 +461,6 @@ static int do_ipv6_setsockopt(struct sock *sk, int level, int optname, > > break; > > } > > > > - fl6_free_socklist(sk); > > __ipv6_sock_mc_close(sk); > > __ipv6_sock_ac_close(sk); > > > > @@ -501,14 +497,9 @@ static int do_ipv6_setsockopt(struct sock *sk, int level, int optname, > > sk->sk_socket->ops = &inet_dgram_ops; > > sk->sk_family = PF_INET; > > } > > - opt = xchg((__force struct ipv6_txoptions **)&np->opt, > > - NULL); > > - if (opt) { > > - atomic_sub(opt->tot_len, &sk->sk_omem_alloc); > > - txopt_put(opt); > > - } > > - pktopt = xchg(&np->pktoptions, NULL); > > - kfree_skb(pktopt); > > + > > Why is this needed ? I think a comment could help. > > + np->rxopt.all = 0;
I added it to reduce the possibility of lockless allocation in ipv6_local_rxpmtu(), which checks np->rxopt.bits.rxpmtu first.
But, lockless sendmsg() even races with this, so it might not be needed or should be added in the next patch?
> > > + inet6_destroy_sock(sk); > > This name is unfortunate. This really is an inet6_cleanup_sock() in > this context.
Ok, I'll add inet6_cleanup_sock() as a wrapper of inet6_destroy_sock() in v3.
And, I'll post a cleanup patch later which renames inet6_destroy_sock() to inet6_cleanup_sock() and removes all unnecessary inet6_destroy_sock() calls in each sk->sk_prot->destroy().
> > > > > /* > > * ... and add it to the refcnt debug socks count > > -- > > 2.30.2
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