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Diffstat (limited to 'net/kcm/kcmsock.c')
-rw-r--r--net/kcm/kcmsock.c16
1 files changed, 14 insertions, 2 deletions
diff --git a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c
index 7632797fb68e..4a8d407f8902 100644
--- a/net/kcm/kcmsock.c
+++ b/net/kcm/kcmsock.c
@@ -1410,9 +1410,18 @@ static int kcm_attach(struct socket *sock, struct socket *csock,
return err;
}
- sock_hold(csk);
-
write_lock_bh(&csk->sk_callback_lock);
+
+ /* Check if sk_user_data is aready by KCM or someone else.
+ * Must be done under lock to prevent race conditions.
+ */
+ if (csk->sk_user_data) {
+ write_unlock_bh(&csk->sk_callback_lock);
+ strp_done(&psock->strp);
+ kmem_cache_free(kcm_psockp, psock);
+ return -EALREADY;
+ }
+
psock->save_data_ready = csk->sk_data_ready;
psock->save_write_space = csk->sk_write_space;
psock->save_state_change = csk->sk_state_change;
@@ -1420,8 +1429,11 @@ static int kcm_attach(struct socket *sock, struct socket *csock,
csk->sk_data_ready = psock_data_ready;
csk->sk_write_space = psock_write_space;
csk->sk_state_change = psock_state_change;
+
write_unlock_bh(&csk->sk_callback_lock);
+ sock_hold(csk);
+
/* Finished initialization, now add the psock to the MUX. */
spin_lock_bh(&mux->lock);
head = &mux->psocks;