diff options
| author | Denis Kenzior <denkenz@gmail.com> | 2016-06-27 11:01:12 -0500 |
|---|---|---|
| committer | Marcel Holtmann <marcel@holtmann.org> | 2016-07-08 12:20:57 +0200 |
| commit | b5f34f9420b50c9b5876b9a2b68e96be6d629054 (patch) | |
| tree | 8bf538e462539a67a35a6b052935d6419cb530e3 | |
| parent | 1c5bf998b3dca0599a2cce885619ffc06fc594df (diff) | |
Bluetooth: Fix bt_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 comple‐
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/af_bluetooth.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/net/bluetooth/af_bluetooth.c b/net/bluetooth/af_bluetooth.c index 3df7aefb7663..ece45e0683fd 100644 --- a/net/bluetooth/af_bluetooth.c +++ b/net/bluetooth/af_bluetooth.c @@ -215,6 +215,7 @@ int bt_sock_recvmsg(struct socket *sock, struct msghdr *msg, size_t len, struct sock *sk = sock->sk; struct sk_buff *skb; size_t copied; + size_t skblen; int err; BT_DBG("sock %p sk %p len %zu", sock, sk, len); @@ -230,6 +231,7 @@ int bt_sock_recvmsg(struct socket *sock, struct msghdr *msg, size_t len, return err; } + skblen = skb->len; copied = skb->len; if (len < copied) { msg->msg_flags |= MSG_TRUNC; @@ -248,6 +250,9 @@ int bt_sock_recvmsg(struct socket *sock, struct msghdr *msg, size_t len, skb_free_datagram(sk, skb); + if (msg->msg_flags & MSG_TRUNC) + copied = skblen; + return err ? : copied; } EXPORT_SYMBOL(bt_sock_recvmsg); |