1 files changed, 87 insertions, 49 deletions

diff --git a/drivers/net/can/slcan.c b/drivers/net/can/slcan.c
index d571e2e9708f..25377e547f9b 100644
--- a/drivers/net/can/slcan.c
+++ b/drivers/net/can/slcan.c
@@ -76,6 +76,10 @@ MODULE_PARM_DESC(maxdev, "Maximum number of slcan interfaces");
 /* maximum rx buffer len: extended CAN frame with timestamp */
 #define SLC_MTU (sizeof("T1111222281122334455667788EA5F\r")+1)
 
+#define SLC_CMD_LEN 1
+#define SLC_SFF_ID_LEN 3
+#define SLC_EFF_ID_LEN 8
+
 struct slcan {
 	int			magic;
 
@@ -142,47 +146,63 @@ static void slc_bump(struct slcan *sl)
 {
 	struct sk_buff *skb;
 	struct can_frame cf;
-	int i, dlc_pos, tmp;
-	unsigned long ultmp;
-	char cmd = sl->rbuff[0];
-
-	if ((cmd != 't') && (cmd != 'T') && (cmd != 'r') && (cmd != 'R'))
+	int i, tmp;
+	u32 tmpid;
+	char *cmd = sl->rbuff;
+
+	cf.can_id = 0;
+
+	switch (*cmd) {
+	case 'r':
+		cf.can_id = CAN_RTR_FLAG;
+		/* fallthrough */
+	case 't':
+		/* store dlc ASCII value and terminate SFF CAN ID string */
+		cf.can_dlc = sl->rbuff[SLC_CMD_LEN + SLC_SFF_ID_LEN];
+		sl->rbuff[SLC_CMD_LEN + SLC_SFF_ID_LEN] = 0;
+		/* point to payload data behind the dlc */
+		cmd += SLC_CMD_LEN + SLC_SFF_ID_LEN + 1;
+		break;
+	case 'R':
+		cf.can_id = CAN_RTR_FLAG;
+		/* fallthrough */
+	case 'T':
+		cf.can_id |= CAN_EFF_FLAG;
+		/* store dlc ASCII value and terminate EFF CAN ID string */
+		cf.can_dlc = sl->rbuff[SLC_CMD_LEN + SLC_EFF_ID_LEN];
+		sl->rbuff[SLC_CMD_LEN + SLC_EFF_ID_LEN] = 0;
+		/* point to payload data behind the dlc */
+		cmd += SLC_CMD_LEN + SLC_EFF_ID_LEN + 1;
+		break;
+	default:
 		return;
+	}
 
-	if (cmd & 0x20) /* tiny chars 'r' 't' => standard frame format */
-		dlc_pos = 4; /* dlc position tiiid */
-	else
-		dlc_pos = 9; /* dlc position Tiiiiiiiid */
-
-	if (!((sl->rbuff[dlc_pos] >= '0') && (sl->rbuff[dlc_pos] < '9')))
+	if (kstrtou32(sl->rbuff + SLC_CMD_LEN, 16, &tmpid))
 		return;
 
-	cf.can_dlc = sl->rbuff[dlc_pos] - '0'; /* get can_dlc from ASCII val */
+	cf.can_id |= tmpid;
 
-	sl->rbuff[dlc_pos] = 0; /* terminate can_id string */
-
-	if (kstrtoul(sl->rbuff+1, 16, &ultmp))
+	/* get can_dlc from sanitized ASCII value */
+	if (cf.can_dlc >= '0' && cf.can_dlc < '9')
+		cf.can_dlc -= '0';
+	else
 		return;
 
-	cf.can_id = ultmp;
-
-	if (!(cmd & 0x20)) /* NO tiny chars => extended frame format */
-		cf.can_id |= CAN_EFF_FLAG;
-
-	if ((cmd | 0x20) == 'r') /* RTR frame */
-		cf.can_id |= CAN_RTR_FLAG;
-
 	*(u64 *) (&cf.data) = 0; /* clear payload */
 
-	for (i = 0, dlc_pos++; i < cf.can_dlc; i++) {
-		tmp = hex_to_bin(sl->rbuff[dlc_pos++]);
-		if (tmp < 0)
-			return;
-		cf.data[i] = (tmp << 4);
-		tmp = hex_to_bin(sl->rbuff[dlc_pos++]);
-		if (tmp < 0)
-			return;
-		cf.data[i] |= tmp;
+	/* RTR frames may have a dlc > 0 but they never have any data bytes */
+	if (!(cf.can_id & CAN_RTR_FLAG)) {
+		for (i = 0; i < cf.can_dlc; i++) {
+			tmp = hex_to_bin(*cmd++);
+			if (tmp < 0)
+				return;
+			cf.data[i] = (tmp << 4);
+			tmp = hex_to_bin(*cmd++);
+			if (tmp < 0)
+				return;
+			cf.data[i] |= tmp;
+		}
 	}
 
 	skb = dev_alloc_skb(sizeof(struct can_frame) +
@@ -209,7 +229,6 @@ static void slc_bump(struct slcan *sl)
 /* parse tty input stream */
 static void slcan_unesc(struct slcan *sl, unsigned char s)
 {
-
 	if ((s == '\r') || (s == '\a')) { /* CR or BEL ends the pdu */
 		if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
 		    (sl->rcount > 4))  {
@@ -236,27 +255,46 @@ static void slcan_unesc(struct slcan *sl, unsigned char s)
 /* Encapsulate one can_frame and stuff into a TTY queue. */
 static void slc_encaps(struct slcan *sl, struct can_frame *cf)
 {
-	int actual, idx, i;
-	char cmd;
+	int actual, i;
+	unsigned char *pos;
+	unsigned char *endpos;
+	canid_t id = cf->can_id;
+
+	pos = sl->xbuff;
 
 	if (cf->can_id & CAN_RTR_FLAG)
-		cmd = 'R'; /* becomes 'r' in standard frame format */
+		*pos = 'R'; /* becomes 'r' in standard frame format (SFF) */
 	else
-		cmd = 'T'; /* becomes 't' in standard frame format */
+		*pos = 'T'; /* becomes 't' in standard frame format (SSF) */
 
-	if (cf->can_id & CAN_EFF_FLAG)
-		sprintf(sl->xbuff, "%c%08X%d", cmd,
-			cf->can_id & CAN_EFF_MASK, cf->can_dlc);
-	else
-		sprintf(sl->xbuff, "%c%03X%d", cmd | 0x20,
-			cf->can_id & CAN_SFF_MASK, cf->can_dlc);
+	/* determine number of chars for the CAN-identifier */
+	if (cf->can_id & CAN_EFF_FLAG) {
+		id &= CAN_EFF_MASK;
+		endpos = pos + SLC_EFF_ID_LEN;
+	} else {
+		*pos |= 0x20; /* convert R/T to lower case for SFF */
+		id &= CAN_SFF_MASK;
+		endpos = pos + SLC_SFF_ID_LEN;
+	}
+
+	/* build 3 (SFF) or 8 (EFF) digit CAN identifier */
+	pos++;
+	while (endpos >= pos) {
+		*endpos-- = hex_asc_upper[id & 0xf];
+		id >>= 4;
+	}
+
+	pos += (cf->can_id & CAN_EFF_FLAG) ? SLC_EFF_ID_LEN : SLC_SFF_ID_LEN;
 
-	idx = strlen(sl->xbuff);
+	*pos++ = cf->can_dlc + '0';
 
-	for (i = 0; i < cf->can_dlc; i++)
-		sprintf(&sl->xbuff[idx + 2*i], "%02X", cf->data[i]);
+	/* RTR frames may have a dlc > 0 but they never have any data bytes */
+	if (!(cf->can_id & CAN_RTR_FLAG)) {
+		for (i = 0; i < cf->can_dlc; i++)
+			pos = hex_byte_pack_upper(pos, cf->data[i]);
+	}
 
-	strcat(sl->xbuff, "\r"); /* add terminating character */
+	*pos++ = '\r';
 
 	/* Order of next two lines is *very* important.
 	 * When we are sending a little amount of data,
@@ -267,8 +305,8 @@ static void slc_encaps(struct slcan *sl, struct can_frame *cf)
 	 *       14 Oct 1994  Dmitry Gorodchanin.
 	 */
 	set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
-	actual = sl->tty->ops->write(sl->tty, sl->xbuff, strlen(sl->xbuff));
-	sl->xleft = strlen(sl->xbuff) - actual;
+	actual = sl->tty->ops->write(sl->tty, sl->xbuff, pos - sl->xbuff);
+	sl->xleft = (pos - sl->xbuff) - actual;
 	sl->xhead = sl->xbuff + actual;
 	sl->dev->stats.tx_bytes += cf->can_dlc;
 }