On Thu, 2018-01-25 at 20:08 +0800, Li RongQing wrote: > Clean the sk_frag.page of new cloned socket, otherwise it will release > twice wrongly since the reference count of this sk_frag page is not > increased. > > sk_clone_lock() is used to clone a new socket from sock which is in > listening state and has not sk_frag.page, but a socket has sent data > and can gets transformed back to a listening socket, will allocate an > tcp_sock through sk_clone_lock() when a new connection comes in. > > Signed-off-by: Li RongQing <lirongq...@baidu.com> > Cc: Eric Dumazet <eduma...@google.com> > --- > net/core/sock.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/net/core/sock.c b/net/core/sock.c > index c0b5b2f17412..c845856f26da 100644 > --- a/net/core/sock.c > +++ b/net/core/sock.c > @@ -1738,6 +1738,8 @@ struct sock *sk_clone_lock(const struct sock *sk, const > gfp_t priority) > sk_refcnt_debug_inc(newsk); > sk_set_socket(newsk, NULL); > newsk->sk_wq = NULL; > + newsk->sk_frag.page = NULL; > + newsk->sk_frag.offset = 0; > > if (newsk->sk_prot->sockets_allocated) > sk_sockets_allocated_inc(newsk);
Good catch. I suspect this was discovered by some syzkaller/syzbot run ? I would rather move that in tcp_disconnect() that only fuzzers use, instead of doing this on every clone and slowing down normal users.
