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>

6 files changed, 31 insertions, 24 deletions

diff --git a/net/caif/cfdbgl.c b/net/caif/cfdbgl.c
index 65d6ef3cf9aa..2914659eb9b2 100644
--- a/net/caif/cfdbgl.c
+++ b/net/caif/cfdbgl.c
@@ -41,8 +41,10 @@ static int cfdbgl_transmit(struct cflayer *layr, struct cfpkt *pkt)
         struct caif_payload_info *info;
         int ret;
 
-        if (!cfsrvl_ready(service, &ret))
+        if (!cfsrvl_ready(service, &ret)) {
+                cfpkt_destroy(pkt);
                 return ret;
+        }
 
         /* Add info for MUX-layer to route the packet out */
         info = cfpkt_info(pkt);
diff --git a/net/caif/cfdgml.c b/net/caif/cfdgml.c
index 0f5ff27aa41c..a63f4a5f5aff 100644
--- a/net/caif/cfdgml.c
+++ b/net/caif/cfdgml.c
@@ -86,12 +86,17 @@ static int cfdgml_transmit(struct cflayer *layr, struct cfpkt *pkt)
         struct caif_payload_info *info;
         struct cfsrvl *service = container_obj(layr);
         int ret;
-        if (!cfsrvl_ready(service, &ret))
+
+        if (!cfsrvl_ready(service, &ret)) {
+                cfpkt_destroy(pkt);
                 return ret;
+        }
 
         /* STE Modem cannot handle more than 1500 bytes datagrams */
-        if (cfpkt_getlen(pkt) > DGM_MTU)
+        if (cfpkt_getlen(pkt) > DGM_MTU) {
+                cfpkt_destroy(pkt);
                 return -EMSGSIZE;
+        }
 
         cfpkt_add_head(pkt, &zero, 3);
         packet_type = 0x08; /* B9 set - UNCLASSIFIED */
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;
diff --git a/net/caif/cfsrvl.c b/net/caif/cfsrvl.c
index b99f5b22689d..4aa33d4496b6 100644
--- a/net/caif/cfsrvl.c
+++ b/net/caif/cfsrvl.c
@@ -174,15 +174,11 @@ void cfsrvl_init(struct cfsrvl *service,
 
 bool cfsrvl_ready(struct cfsrvl *service, int *err)
 {
-        if (service->open && service->modem_flow_on && service->phy_flow_on)
-                return true;
         if (!service->open) {
                 *err = -ENOTCONN;
                 return false;
         }
-        caif_assert(!(service->modem_flow_on && service->phy_flow_on));
-        *err = -EAGAIN;
-        return false;
+        return true;
 }
 
 u8 cfsrvl_getphyid(struct cflayer *layer)
diff --git a/net/caif/cfutill.c b/net/caif/cfutill.c
index 53e49f3e3af3..86d2dadb4b73 100644
--- a/net/caif/cfutill.c
+++ b/net/caif/cfutill.c
@@ -84,8 +84,11 @@ static int cfutill_transmit(struct cflayer *layr, struct cfpkt *pkt)
         caif_assert(layr != NULL);
         caif_assert(layr->dn != NULL);
         caif_assert(layr->dn->transmit != NULL);
-        if (!cfsrvl_ready(service, &ret))
+
+        if (!cfsrvl_ready(service, &ret)) {
+                cfpkt_destroy(pkt);
                 return ret;
+        }
 
         cfpkt_add_head(pkt, &zero, 1);
         /* Add info for MUX-layer to route the packet out. */
diff --git a/net/caif/cfvidl.c b/net/caif/cfvidl.c
index e3f37db40ac3..a8e2a2d758a5 100644
--- a/net/caif/cfvidl.c
+++ b/net/caif/cfvidl.c
@@ -50,8 +50,12 @@ static int cfvidl_transmit(struct cflayer *layr, struct cfpkt *pkt)
         struct caif_payload_info *info;
         u32 videoheader = 0;
         int ret;
-        if (!cfsrvl_ready(service, &ret))
+
+        if (!cfsrvl_ready(service, &ret)) {
+                cfpkt_destroy(pkt);
                 return ret;
+        }
+
         cfpkt_add_head(pkt, &videoheader, 4);
         /* Add info for MUX-layer to route the packet out */
         info = cfpkt_info(pkt);