caif: Fix for a race in socket transmit with flow control.

Kill faulty checks on flow-off leading to connection drop at race conditions.
caif_socket checks for flow-on before transmitting and goes to sleep or
return -EAGAIN upon flow stop. Remove faulty subsequent checks on flow-off
leading to connection drop. Also fix memory leaks on some of the errors paths.

Signed-off-by: Sjur Brændeland <sjur.brandeland@stericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 11 insertions, 14 deletions

diff --git a/net/caif/cfrfml.c b/net/caif/cfrfml.c
index 6dc75d4f8d94..2b563ad04597 100644
--- a/net/caif/cfrfml.c
+++ b/net/caif/cfrfml.c
@@ -184,6 +184,11 @@ out:
 					rfml->serv.dev_info.id);
 	}
 	spin_unlock(&rfml->sync);
+
+	if (unlikely(err == -EAGAIN))
+		/* It is not possible to recover after drop of a fragment */
+		err = -EIO;
+
 	return err;
 }
 
@@ -218,7 +223,7 @@ static int cfrfml_transmit(struct cflayer *layr, struct cfpkt *pkt)
 	caif_assert(layr->dn->transmit != NULL);
 
 	if (!cfsrvl_ready(&rfml->serv, &err))
-		return err;
+		goto out;
 
 	err = -EPROTO;
 	if (cfpkt_getlen(pkt) <= RFM_HEAD_SIZE-1)
@@ -251,8 +256,11 @@ static int cfrfml_transmit(struct cflayer *layr, struct cfpkt *pkt)
 
 		err = cfrfml_transmit_segment(rfml, frontpkt);
 
-		if (err != 0)
+		if (err != 0) {
+			frontpkt = NULL;
 			goto out;
+		}
+
 		frontpkt = rearpkt;
 		rearpkt = NULL;
 
@@ -286,19 +294,8 @@ out:
 		if (rearpkt)
 			cfpkt_destroy(rearpkt);
 
-		if (frontpkt && frontpkt != pkt) {
-
+		if (frontpkt)
 			cfpkt_destroy(frontpkt);
-			/*
-			 * Socket layer will free the original packet,
-			 * but this packet may already be sent and
-			 * freed. So we have to return 0 in this case
-			 * to avoid socket layer to re-free this packet.
-			 * The return of shutdown indication will
-			 * cause connection to be invalidated anyhow.
-			 */
-			err = 0;
-		}
 	}
 
 	return err;