diff options
| author | Or Cohen <orcohen@paloaltonetworks.com> | 2021-04-13 21:10:31 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2021-04-13 14:59:46 -0700 |
| commit | b166a20b07382b8bc1dcee2a448715c9c2c81b5b (patch) | |
| tree | ddc605b5d010d800b84225d1113abb26641e95a4 /net/sctp/socket.c | |
| parent | ca09bf7bb109a37a7ff05f230bb3fa3627e6625f (diff) | |
net/sctp: fix race condition in sctp_destroy_sock
If sctp_destroy_sock is called without sock_net(sk)->sctp.addr_wq_lock
held and sp->do_auto_asconf is true, then an element is removed
from the auto_asconf_splist without any proper locking.
This can happen in the following functions:
1. In sctp_accept, if sctp_sock_migrate fails.
2. In inet_create or inet6_create, if there is a bpf program
attached to BPF_CGROUP_INET_SOCK_CREATE which denies
creation of the sctp socket.
The bug is fixed by acquiring addr_wq_lock in sctp_destroy_sock
instead of sctp_close.
This addresses CVE-2021-23133.
Reported-by: Or Cohen <orcohen@paloaltonetworks.com>
Reviewed-by: Xin Long <lucien.xin@gmail.com>
Fixes: 610236587600 ("bpf: Add new cgroup attach type to enable sock modifications")
Signed-off-by: Or Cohen <orcohen@paloaltonetworks.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/sctp/socket.c')
| -rw-r--r-- | net/sctp/socket.c | 13 |
1 files changed, 5 insertions, 8 deletions
diff --git a/net/sctp/socket.c b/net/sctp/socket.c index a710917c5ac7..b9b3d899a611 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -1520,11 +1520,9 @@ static void sctp_close(struct sock *sk, long timeout) /* Supposedly, no process has access to the socket, but * the net layers still may. - * Also, sctp_destroy_sock() needs to be called with addr_wq_lock - * held and that should be grabbed before socket lock. */ - spin_lock_bh(&net->sctp.addr_wq_lock); - bh_lock_sock_nested(sk); + local_bh_disable(); + bh_lock_sock(sk); /* Hold the sock, since sk_common_release() will put sock_put() * and we have just a little more cleanup. @@ -1533,7 +1531,7 @@ static void sctp_close(struct sock *sk, long timeout) sk_common_release(sk); bh_unlock_sock(sk); - spin_unlock_bh(&net->sctp.addr_wq_lock); + local_bh_enable(); sock_put(sk); @@ -4993,9 +4991,6 @@ static int sctp_init_sock(struct sock *sk) sk_sockets_allocated_inc(sk); sock_prot_inuse_add(net, sk->sk_prot, 1); - /* Nothing can fail after this block, otherwise - * sctp_destroy_sock() will be called without addr_wq_lock held - */ if (net->sctp.default_auto_asconf) { spin_lock(&sock_net(sk)->sctp.addr_wq_lock); list_add_tail(&sp->auto_asconf_list, @@ -5030,7 +5025,9 @@ static void sctp_destroy_sock(struct sock *sk) if (sp->do_auto_asconf) { sp->do_auto_asconf = 0; + spin_lock_bh(&sock_net(sk)->sctp.addr_wq_lock); list_del(&sp->auto_asconf_list); + spin_unlock_bh(&sock_net(sk)->sctp.addr_wq_lock); } sctp_endpoint_free(sp->ep); local_bh_disable(); |