diff options
| author | Paolo Abeni <pabeni@redhat.com> | 2021-06-09 11:49:01 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2021-06-09 14:08:41 -0700 |
| commit | a8b897c7bcd47f4147d066e22cc01d1026d7640e (patch) | |
| tree | f8423df1a5a624483c4cbd8c53fc7e0c05708fab /net | |
| parent | dcd01eeac14486b56a790f5cce9b823440ba5b34 (diff) | |
udp: fix race between close() and udp_abort()
Kaustubh reported and diagnosed a panic in udp_lib_lookup().
The root cause is udp_abort() racing with close(). Both
racing functions acquire the socket lock, but udp{v6}_destroy_sock()
release it before performing destructive actions.
We can't easily extend the socket lock scope to avoid the race,
instead use the SOCK_DEAD flag to prevent udp_abort from doing
any action when the critical race happens.
Diagnosed-and-tested-by: Kaustubh Pandey <kapandey@codeaurora.org>
Fixes: 5d77dca82839 ("net: diag: support SOCK_DESTROY for UDP sockets")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv4/udp.c | 10 | ||||
| -rw-r--r-- | net/ipv6/udp.c | 3 |
2 files changed, 13 insertions, 0 deletions
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index 15f5504adf5b..1307ad0d3b9e 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -2607,6 +2607,9 @@ void udp_destroy_sock(struct sock *sk) { struct udp_sock *up = udp_sk(sk); bool slow = lock_sock_fast(sk); + + /* protects from races with udp_abort() */ + sock_set_flag(sk, SOCK_DEAD); udp_flush_pending_frames(sk); unlock_sock_fast(sk, slow); if (static_branch_unlikely(&udp_encap_needed_key)) { @@ -2857,10 +2860,17 @@ int udp_abort(struct sock *sk, int err) { lock_sock(sk); + /* udp{v6}_destroy_sock() sets it under the sk lock, avoid racing + * with close() + */ + if (sock_flag(sk, SOCK_DEAD)) + goto out; + sk->sk_err = err; sk->sk_error_report(sk); __udp_disconnect(sk, 0); +out: release_sock(sk); return 0; diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c index 199b080d418a..3fcd86f4dfdc 100644 --- a/net/ipv6/udp.c +++ b/net/ipv6/udp.c @@ -1598,6 +1598,9 @@ void udpv6_destroy_sock(struct sock *sk) { struct udp_sock *up = udp_sk(sk); lock_sock(sk); + + /* protects from races with udp_abort() */ + sock_set_flag(sk, SOCK_DEAD); udp_v6_flush_pending_frames(sk); release_sock(sk); |