Messages in this thread | | | From | Kuniyuki Iwashima <> | Subject | Re: [PATCH v1 net 3/5] tcp/udp: Call inet6_destroy_sock() in IPv4 sk_prot->destroy(). | Date | Tue, 27 Sep 2022 10:02:39 -0700 |
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From: Eric Dumazet <edumazet@google.com> Date: Tue, 27 Sep 2022 09:50:04 -0700 > On Tue, Sep 27, 2022 at 9:13 AM Kuniyuki Iwashima <kuniyu@amazon.com> wrote: > > > > Originally, inet6_sk(sk)->XXX were changed under lock_sock(), so we were > > able to clean them up by calling inet6_destroy_sock() during the IPv6 -> > > IPv4 conversion by IPV6_ADDRFORM. However, commit 03485f2adcde ("udpv6: > > Add lockless sendmsg() support") added a lockless memory allocation path, > > which could cause a memory leak: > > > > setsockopt(IPV6_ADDRFORM) sendmsg() > > +-----------------------+ +-------+ > > - do_ipv6_setsockopt(sk, ...) - udpv6_sendmsg(sk, ...) > > - lock_sock(sk) ^._ called via udpv6_prot > > - WRITE_ONCE(sk->sk_prot, &tcp_prot) before WRITE_ONCE() > > - inet6_destroy_sock() > > - release_sock(sk) - ip6_make_skb(sk, ...) > > ^._ lockless fast path for > > the non-corking case > > > > - __ip6_append_data(sk, ...) > > - ipv6_local_rxpmtu(sk, ...) > > - xchg(&np->rxpmtu, skb) > > ^._ rxpmtu is never freed. > > > > - lock_sock(sk) > > > > For now, rxpmtu is only the case, but let's call inet6_destroy_sock() > > in both TCP/UDP v4 destroy functions not to miss the future change. > > > > We can consolidate TCP/UDP v4/v6 destroy functions, but such changes > > are too invasive to backport to stable. So, they can be posted as a > > follow-up later for net-next. > > > > Fixes: 03485f2adcde ("udpv6: Add lockless sendmsg() support") > > Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> > > --- > > Cc: Vladislav Yasevich <vyasevic@redhat.com> > > --- > > net/ipv4/tcp_ipv4.c | 5 +++++ > > net/ipv4/udp.c | 6 ++++++ > > net/ipv6/tcp_ipv6.c | 1 - > > 3 files changed, 11 insertions(+), 1 deletion(-) > > > > diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c > > index 5b019ba2b9d2..035b6c52a243 100644 > > --- a/net/ipv4/tcp_ipv4.c > > +++ b/net/ipv4/tcp_ipv4.c > > @@ -2263,6 +2263,11 @@ void tcp_v4_destroy_sock(struct sock *sk) > > tcp_saved_syn_free(tp); > > > > sk_sockets_allocated_dec(sk); > > + > > +#if IS_ENABLED(CONFIG_IPV6) > > + if (sk->sk_prot_creator == &tcpv6_prot) > > + inet6_destroy_sock(sk); > > +#endif > > } > > This is ugly, and will not compile with CONFIG_IPV6=m, right ?
Ah, exactly...
ld: net/ipv4/tcp_ipv4.o: in function `tcp_v4_destroy_sock': /mnt/ec2-user/kernel/214_tcp_ipv6_renew_options_memleak/net/ipv4/tcp_ipv4.c:2290: undefined reference to `tcpv6_prot' ld: /mnt/ec2-user/kernel/214_tcp_ipv6_renew_options_memleak/net/ipv4/tcp_ipv4.c:2291: undefined reference to `inet6_destroy_sock' ld: net/ipv4/udp.o: in function `udp_destroy_sock': /mnt/ec2-user/kernel/214_tcp_ipv6_renew_options_memleak/net/ipv4/udp.c:2660: undefined reference to `udpv6_prot' ld: /mnt/ec2-user/kernel/214_tcp_ipv6_renew_options_memleak/net/ipv4/udp.c:2661: undefined reference to `inet6_destroy_sock'
So, do we have to move these 4 under net/ipv4/ with #ifdef CONFIG_IPv6 ?
> > EXPORT_SYMBOL(tcp_v4_destroy_sock); > > > > diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c > > index 560d9eadeaa5..cdf131c0a819 100644 > > --- a/net/ipv4/udp.c > > +++ b/net/ipv4/udp.c > > @@ -115,6 +115,7 @@ > > #include <net/udp_tunnel.h> > > #if IS_ENABLED(CONFIG_IPV6) > > #include <net/ipv6_stubs.h> > > +#include <net/transp_v6.h> > > #endif > > > > struct udp_table udp_table __read_mostly; > > @@ -2666,6 +2667,11 @@ void udp_destroy_sock(struct sock *sk) > > if (up->encap_enabled) > > static_branch_dec(&udp_encap_needed_key); > > } > > + > > +#if IS_ENABLED(CONFIG_IPV6) > > + if (sk->sk_prot_creator == &udpv6_prot) > > + inet6_destroy_sock(sk); > > +#endif > > } > > > > /* > > diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c > > index e54eee80ce5f..1ff6a92f7774 100644 > > --- a/net/ipv6/tcp_ipv6.c > > +++ b/net/ipv6/tcp_ipv6.c > > @@ -1945,7 +1945,6 @@ static int tcp_v6_init_sock(struct sock *sk) > > static void tcp_v6_destroy_sock(struct sock *sk) > > { > > tcp_v4_destroy_sock(sk); > > - inet6_destroy_sock(sk); > > } > > > > #ifdef CONFIG_PROC_FS > > -- > > 2.30.2 > >
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