linux-stable/net/ipv6/udp_impl.h
Kuniyuki Iwashima d38afeec26 tcp/udp: Call inet6_destroy_sock() in IPv6 sk->sk_destruct().
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 03485f2adc ("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, ...)
  - sockopt_lock_sock(sk)                   ^._ called via udpv6_prot
    - lock_sock(sk)                             before WRITE_ONCE()
  - WRITE_ONCE(sk->sk_prot, &tcp_prot)
  - inet6_destroy_sock()                    - if (!corkreq)
  - sockopt_release_sock(sk)                  - ip6_make_skb(sk, ...)
    - release_sock(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.

                                                - goto out_no_dst;

                                            - lock_sock(sk)

For now, rxpmtu is only the case, but not to miss the future change
and a similar bug fixed in commit e27326009a ("net: ping6: Fix
memleak in ipv6_renew_options()."), let's set a new function to IPv6
sk->sk_destruct() and call inet6_cleanup_sock() there.  Since the
conversion does not change sk->sk_destruct(), we can guarantee that
we can clean up IPv6 resources finally.

We can now remove all inet6_destroy_sock() calls from IPv6 protocol
specific ->destroy() functions, but such changes are invasive to
backport.  So they can be posted as a follow-up later for net-next.

Fixes: 03485f2adc ("udpv6: Add lockless sendmsg() support")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-10-12 17:50:37 -07:00

31 lines
1.1 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _UDP6_IMPL_H
#define _UDP6_IMPL_H
#include <net/udp.h>
#include <net/udplite.h>
#include <net/protocol.h>
#include <net/addrconf.h>
#include <net/inet_common.h>
#include <net/transp_v6.h>
int __udp6_lib_rcv(struct sk_buff *, struct udp_table *, int);
int __udp6_lib_err(struct sk_buff *, struct inet6_skb_parm *, u8, u8, int,
__be32, struct udp_table *);
int udpv6_init_sock(struct sock *sk);
int udp_v6_get_port(struct sock *sk, unsigned short snum);
void udp_v6_rehash(struct sock *sk);
int udpv6_getsockopt(struct sock *sk, int level, int optname,
char __user *optval, int __user *optlen);
int udpv6_setsockopt(struct sock *sk, int level, int optname, sockptr_t optval,
unsigned int optlen);
int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len);
int udpv6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int flags,
int *addr_len);
void udpv6_destroy_sock(struct sock *sk);
#ifdef CONFIG_PROC_FS
int udp6_seq_show(struct seq_file *seq, void *v);
#endif
#endif /* _UDP6_IMPL_H */