From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: Wei Xu Date: Fri, 1 Dec 2017 05:10:37 -0500 Subject: [PATCH] tun: free skb in early errors MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit tun_recvmsg() supports accepting skb by msg_control after commit ac77cfd4258f ("tun: support receiving skb through msg_control"), the skb if presented should be freed no matter how far it can go along, otherwise it would be leaked. This patch fixes several missed cases. Signed-off-by: Wei Xu Reported-by: Matthew Rosato Signed-off-by: Fabian Grünbichler --- drivers/net/tun.c | 24 ++++++++++++++++++------ 1 file changed, 18 insertions(+), 6 deletions(-) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index cb1f7747adad..5143e948d7d1 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -1519,8 +1519,11 @@ static ssize_t tun_do_read(struct tun_struct *tun, struct tun_file *tfile, tun_debug(KERN_INFO, tun, "tun_do_read\n"); - if (!iov_iter_count(to)) + if (!iov_iter_count(to)) { + if (skb) + kfree_skb(skb); return 0; + } if (!skb) { /* Read frames from ring */ @@ -1636,22 +1639,24 @@ static int tun_recvmsg(struct socket *sock, struct msghdr *m, size_t total_len, { struct tun_file *tfile = container_of(sock, struct tun_file, socket); struct tun_struct *tun = __tun_get(tfile); + struct sk_buff *skb = m->msg_control; int ret; - if (!tun) - return -EBADFD; + if (!tun) { + ret = -EBADFD; + goto out_free_skb; + } if (flags & ~(MSG_DONTWAIT|MSG_TRUNC|MSG_ERRQUEUE)) { ret = -EINVAL; - goto out; + goto out_put_tun; } if (flags & MSG_ERRQUEUE) { ret = sock_recv_errqueue(sock->sk, m, total_len, SOL_PACKET, TUN_TX_TIMESTAMP); goto out; } - ret = tun_do_read(tun, tfile, &m->msg_iter, flags & MSG_DONTWAIT, - m->msg_control); + ret = tun_do_read(tun, tfile, &m->msg_iter, flags & MSG_DONTWAIT, skb); if (ret > (ssize_t)total_len) { m->msg_flags |= MSG_TRUNC; ret = flags & MSG_TRUNC ? ret : total_len; @@ -1659,6 +1664,13 @@ static int tun_recvmsg(struct socket *sock, struct msghdr *m, size_t total_len, out: tun_put(tun); return ret; + +out_put_tun: + tun_put(tun); +out_free_skb: + if (skb) + kfree_skb(skb); + return ret; } static int tun_peek_len(struct socket *sock) -- 2.14.2