[PATCH] core: Fix wrong expectations for the return of recv()

[PATCH] core: Fix wrong expectations for the return of recv()

[Vinicius Costa Gomes]

Since commit b5f34f9420b50 "Bluetooth: Fix bt_sock_recvmsg return value"
in the kernel, Bluetooth sockets of type SOCK_SEQPACKET, when read()
will return the size of the packet received, which can be larger than
the the buffer passed by user space.

In this case the problem was causing a disconnection soon after
the reception of an SDP request.

Reported by: Alban Browaeys <prahal@yahoo.com>
---
 src/sdpd-server.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/sdpd-server.c b/src/sdpd-server.c
index c863508..b8190da 100644
--- a/src/sdpd-server.c
+++ b/src/sdpd-server.c
@@ -164,7 +164,7 @@ static gboolean io_session_event(GIOChannel *chan, GIOCondition cond, gpointer d
 	}
 
 	len = recv(sk, &hdr, sizeof(sdp_pdu_hdr_t), MSG_PEEK);
-	if (len != sizeof(sdp_pdu_hdr_t)) {
+	if (len < sizeof(sdp_pdu_hdr_t)) {
 		sdp_svcdb_collect_all(sk);
 		return FALSE;
 	}
-- 
2.9.2

Re: [PATCH] core: Fix wrong expectations for the return of recv()

[Luiz Augusto von Dentz]

Hi Vinicius,

On Thu, Aug 11, 2016 at 1:14 AM, Vinicius Costa Gomes <vcgomes@gmail.com> wrote:
> Since commit b5f34f9420b50 "Bluetooth: Fix bt_sock_recvmsg return value"
> in the kernel, Bluetooth sockets of type SOCK_SEQPACKET, when read()
> will return the size of the packet received, which can be larger than
> the the buffer passed by user space.
>
> In this case the problem was causing a disconnection soon after
> the reception of an SDP request.
>
> Reported by: Alban Browaeys <prahal@yahoo.com>
> ---
>  src/sdpd-server.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/src/sdpd-server.c b/src/sdpd-server.c
> index c863508..b8190da 100644
> --- a/src/sdpd-server.c
> +++ b/src/sdpd-server.c
> @@ -164,7 +164,7 @@ static gboolean io_session_event(GIOChannel *chan, GIOCondition cond, gpointer d
>         }
>
>         len = recv(sk, &hdr, sizeof(sdp_pdu_hdr_t), MSG_PEEK);
> -       if (len != sizeof(sdp_pdu_hdr_t)) {
> +       if (len < sizeof(sdp_pdu_hdr_t)) {
>                 sdp_svcdb_collect_all(sk);
>                 return FALSE;
>         }
> --
> 2.9.2

Applied, note that I did have to include a cast since it was causing
and signess comparison error.

-- 
Luiz Augusto von Dentz