2016-08-10 22:14:28

by Vinicius Costa Gomes

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

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 <[email protected]>
---
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

2016-08-12 07:57:10

by Luiz Augusto von Dentz

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

Hi Vinicius,

On Thu, Aug 11, 2016 at 1:14 AM, Vinicius Costa Gomes <[email protected]> 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 <[email protected]>
> ---
> 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