diff options
author | Denis Kenzior <denkenz@gmail.com> | 2016-06-27 11:01:13 -0500 |
---|---|---|
committer | Marcel Holtmann <marcel@holtmann.org> | 2016-07-08 12:20:57 +0200 |
commit | 83871f8ccdfa8f3edab15d432aa4f3eb82953343 (patch) | |
tree | 7211e3ea042d070769d2ede39b81a1056582a8c1 | |
parent | b5f34f9420b50c9b5876b9a2b68e96be6d629054 (diff) |
Bluetooth: Fix hci_sock_recvmsg return value
If recvmsg is called with a destination buffer that is too small to
receive the contents of skb in its entirety, the return value from
recvmsg was inconsistent with common SOCK_SEQPACKET or SOCK_DGRAM
semantics.
If destination buffer provided by userspace is too small (e.g. len <
copied), then MSG_TRUNC flag is set and copied is returned. Instead, it
should return the length of the message, which is consistent with how
other datagram based sockets act. Quoting 'man recv':
"All three calls return the length of the message on successful compleā
tion. If a message is too long to fit in the supplied buffer, excess
bytes may be discarded depending on the type of socket the message is
received from."
and
"MSG_TRUNC (since Linux 2.2)
For raw (AF_PACKET), Internet datagram (since Linux
2.4.27/2.6.8), netlink (since Linux 2.6.22), and UNIX datagram
(since Linux 3.4) sockets: return the real length of the packet
or datagram, even when it was longer than the passed buffer."
Signed-off-by: Denis Kenzior <denkenz@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
-rw-r--r-- | net/bluetooth/hci_sock.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/net/bluetooth/hci_sock.c b/net/bluetooth/hci_sock.c index 1298d723c0e0..12e9294b02e0 100644 --- a/net/bluetooth/hci_sock.c +++ b/net/bluetooth/hci_sock.c @@ -1048,6 +1048,7 @@ static int hci_sock_recvmsg(struct socket *sock, struct msghdr *msg, struct sock *sk = sock->sk; struct sk_buff *skb; int copied, err; + unsigned int skblen; BT_DBG("sock %p, sk %p", sock, sk); @@ -1064,6 +1065,7 @@ static int hci_sock_recvmsg(struct socket *sock, struct msghdr *msg, if (!skb) return err; + skblen = skb->len; copied = skb->len; if (len < copied) { msg->msg_flags |= MSG_TRUNC; @@ -1089,6 +1091,9 @@ static int hci_sock_recvmsg(struct socket *sock, struct msghdr *msg, skb_free_datagram(sk, skb); + if (msg->msg_flags & MSG_TRUNC) + copied = skblen; + return err ? : copied; } |