3 files changed, 74 insertions, 12 deletions

diff --git a/net/can/af_can.c b/net/can/af_can.c
index 4c343b43067f..837bb8af0ec3 100644
--- a/net/can/af_can.c
+++ b/net/can/af_can.c
@@ -891,7 +891,7 @@ static __init int can_init(void)
 	int err;
 
 	/* check for correct padding to be able to use the structs similarly */
-	BUILD_BUG_ON(offsetof(struct can_frame, can_dlc) !=
+	BUILD_BUG_ON(offsetof(struct can_frame, len) !=
 		     offsetof(struct canfd_frame, len) ||
 		     offsetof(struct can_frame, data) !=
 		     offsetof(struct canfd_frame, data));
diff --git a/net/can/gw.c b/net/can/gw.c
index 6b790b6ff8d2..8598d9da0e5f 100644
--- a/net/can/gw.c
+++ b/net/can/gw.c
@@ -199,6 +199,68 @@ static void mod_set_fddata(struct canfd_frame *cf, struct cf_mod *mod)
 	memcpy(cf->data, mod->modframe.set.data, CANFD_MAX_DLEN);
 }
 
+/* retrieve valid CC DLC value and store it into 'len' */
+static void mod_retrieve_ccdlc(struct canfd_frame *cf)
+{
+	struct can_frame *ccf = (struct can_frame *)cf;
+
+	/* len8_dlc is only valid if len == CAN_MAX_DLEN */
+	if (ccf->len != CAN_MAX_DLEN)
+		return;
+
+	/* do we have a valid len8_dlc value from 9 .. 15 ? */
+	if (ccf->len8_dlc > CAN_MAX_DLEN && ccf->len8_dlc <= CAN_MAX_RAW_DLC)
+		ccf->len = ccf->len8_dlc;
+}
+
+/* convert valid CC DLC value in 'len' into struct can_frame elements */
+static void mod_store_ccdlc(struct canfd_frame *cf)
+{
+	struct can_frame *ccf = (struct can_frame *)cf;
+
+	/* clear potential leftovers */
+	ccf->len8_dlc = 0;
+
+	/* plain data length 0 .. 8 - that was easy */
+	if (ccf->len <= CAN_MAX_DLEN)
+		return;
+
+	/* potentially broken values are catched in can_can_gw_rcv() */
+	if (ccf->len > CAN_MAX_RAW_DLC)
+		return;
+
+	/* we have a valid dlc value from 9 .. 15 in ccf->len */
+	ccf->len8_dlc = ccf->len;
+	ccf->len = CAN_MAX_DLEN;
+}
+
+static void mod_and_ccdlc(struct canfd_frame *cf, struct cf_mod *mod)
+{
+	mod_retrieve_ccdlc(cf);
+	mod_and_len(cf, mod);
+	mod_store_ccdlc(cf);
+}
+
+static void mod_or_ccdlc(struct canfd_frame *cf, struct cf_mod *mod)
+{
+	mod_retrieve_ccdlc(cf);
+	mod_or_len(cf, mod);
+	mod_store_ccdlc(cf);
+}
+
+static void mod_xor_ccdlc(struct canfd_frame *cf, struct cf_mod *mod)
+{
+	mod_retrieve_ccdlc(cf);
+	mod_xor_len(cf, mod);
+	mod_store_ccdlc(cf);
+}
+
+static void mod_set_ccdlc(struct canfd_frame *cf, struct cf_mod *mod)
+{
+	mod_set_len(cf, mod);
+	mod_store_ccdlc(cf);
+}
+
 static void canframecpy(struct canfd_frame *dst, struct can_frame *src)
 {
 	/* Copy the struct members separately to ensure that no uninitialized
@@ -207,7 +269,7 @@ static void canframecpy(struct canfd_frame *dst, struct can_frame *src)
 	 */
 
 	dst->can_id = src->can_id;
-	dst->len = src->can_dlc;
+	dst->len = src->len;
 	*(u64 *)dst->data = *(u64 *)src->data;
 }
 
@@ -842,8 +904,8 @@ static int cgw_parse_attr(struct nlmsghdr *nlh, struct cf_mod *mod,
 			if (mb.modtype & CGW_MOD_ID)
 				mod->modfunc[modidx++] = mod_and_id;
 
-			if (mb.modtype & CGW_MOD_LEN)
-				mod->modfunc[modidx++] = mod_and_len;
+			if (mb.modtype & CGW_MOD_DLC)
+				mod->modfunc[modidx++] = mod_and_ccdlc;
 
 			if (mb.modtype & CGW_MOD_DATA)
 				mod->modfunc[modidx++] = mod_and_data;
@@ -858,8 +920,8 @@ static int cgw_parse_attr(struct nlmsghdr *nlh, struct cf_mod *mod,
 			if (mb.modtype & CGW_MOD_ID)
 				mod->modfunc[modidx++] = mod_or_id;
 
-			if (mb.modtype & CGW_MOD_LEN)
-				mod->modfunc[modidx++] = mod_or_len;
+			if (mb.modtype & CGW_MOD_DLC)
+				mod->modfunc[modidx++] = mod_or_ccdlc;
 
 			if (mb.modtype & CGW_MOD_DATA)
 				mod->modfunc[modidx++] = mod_or_data;
@@ -874,8 +936,8 @@ static int cgw_parse_attr(struct nlmsghdr *nlh, struct cf_mod *mod,
 			if (mb.modtype & CGW_MOD_ID)
 				mod->modfunc[modidx++] = mod_xor_id;
 
-			if (mb.modtype & CGW_MOD_LEN)
-				mod->modfunc[modidx++] = mod_xor_len;
+			if (mb.modtype & CGW_MOD_DLC)
+				mod->modfunc[modidx++] = mod_xor_ccdlc;
 
 			if (mb.modtype & CGW_MOD_DATA)
 				mod->modfunc[modidx++] = mod_xor_data;
@@ -890,8 +952,8 @@ static int cgw_parse_attr(struct nlmsghdr *nlh, struct cf_mod *mod,
 			if (mb.modtype & CGW_MOD_ID)
 				mod->modfunc[modidx++] = mod_set_id;
 
-			if (mb.modtype & CGW_MOD_LEN)
-				mod->modfunc[modidx++] = mod_set_len;
+			if (mb.modtype & CGW_MOD_DLC)
+				mod->modfunc[modidx++] = mod_set_ccdlc;
 
 			if (mb.modtype & CGW_MOD_DATA)
 				mod->modfunc[modidx++] = mod_set_data;
diff --git a/net/can/j1939/main.c b/net/can/j1939/main.c
index 137054bff9ec..bb914d8b4216 100644
--- a/net/can/j1939/main.c
+++ b/net/can/j1939/main.c
@@ -62,7 +62,7 @@ static void j1939_can_recv(struct sk_buff *iskb, void *data)
 	skb_pull(skb, J1939_CAN_HDR);
 
 	/* fix length, set to dlc, with 8 maximum */
-	skb_trim(skb, min_t(uint8_t, cf->can_dlc, 8));
+	skb_trim(skb, min_t(uint8_t, cf->len, 8));
 
 	/* set addr */
 	skcb = j1939_skb_to_cb(skb);
@@ -335,7 +335,7 @@ int j1939_send_one(struct j1939_priv *priv, struct sk_buff *skb)
 		canid |= skcb->addr.da << 8;
 
 	cf->can_id = canid;
-	cf->can_dlc = dlc;
+	cf->len = dlc;
 
 	return can_send(skb, 1);