V4L/DVB (13237): firedtv: length field corrupt in ca2host if length>127

This solves a problem in firedtv that has become major for Swedish DVB-T
users the last month or so.  It will most likely solve issues seen by
other users as well.

If the length of an AVC message is greater than 127, the length field
should be encoded in LV mode instead of V mode. V mode can only be used
if the length is 127 or less. This patch ensures that the CA_PMT
message is always encoded in LV mode so PMT message of greater lengths
can be supported.

Signed-off-by: Henrik Kurelid <henrik@kurelid.se>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 20 insertions, 18 deletions

diff --git a/drivers/media/dvb/firewire/firedtv-avc.c b/drivers/media/dvb/firewire/firedtv-avc.c
index d1b67fe..485d061 100644
--- a/drivers/media/dvb/firewire/firedtv-avc.c
+++ b/drivers/media/dvb/firewire/firedtv-avc.c
@@ -1050,28 +1050,28 @@ int avc_ca_pmt(struct firedtv *fdtv, char *msg, int length)
 	c->operand[4] = 0; /* slot */
 	c->operand[5] = SFE_VENDOR_TAG_CA_PMT; /* ca tag */
 	c->operand[6] = 0; /* more/last */
-	/* c->operand[7] = XXXprogram_info_length + 17; */ /* length */
-	c->operand[8] = list_management;
-	c->operand[9] = 0x01; /* pmt_cmd=OK_descramble */
+	/* Use three bytes for length field in case length > 127 */
+	c->operand[10] = list_management;
+	c->operand[11] = 0x01; /* pmt_cmd=OK_descramble */
 
 	/* TS program map table */
 
-	c->operand[10] = 0x02; /* Table id=2 */
-	c->operand[11] = 0x80; /* Section syntax + length */
-	/* c->operand[12] = XXXprogram_info_length + 12; */
-	c->operand[13] = msg[1]; /* Program number */
-	c->operand[14] = msg[2];
-	c->operand[15] = 0x01; /* Version number=0 + current/next=1 */
-	c->operand[16] = 0x00; /* Section number=0 */
-	c->operand[17] = 0x00; /* Last section number=0 */
-	c->operand[18] = 0x1f; /* PCR_PID=1FFF */
-	c->operand[19] = 0xff;
-	c->operand[20] = (program_info_length >> 8); /* Program info length */
-	c->operand[21] = (program_info_length & 0xff);
+	c->operand[12] = 0x02; /* Table id=2 */
+	c->operand[13] = 0x80; /* Section syntax + length */
+	/* c->operand[14] = XXXprogram_info_length + 12; */
+	c->operand[15] = msg[1]; /* Program number */
+	c->operand[16] = msg[2];
+	c->operand[17] = 0x01; /* Version number=0 + current/next=1 */
+	c->operand[18] = 0x00; /* Section number=0 */
+	c->operand[19] = 0x00; /* Last section number=0 */
+	c->operand[20] = 0x1f; /* PCR_PID=1FFF */
+	c->operand[21] = 0xff;
+	c->operand[22] = (program_info_length >> 8); /* Program info length */
+	c->operand[23] = (program_info_length & 0xff);
 
 	/* CA descriptors at programme level */
 	read_pos = 6;
-	write_pos = 22;
+	write_pos = 24;
 	if (program_info_length > 0) {
 		pmt_cmd_id = msg[read_pos++];
 		if (pmt_cmd_id != 1 && pmt_cmd_id != 4)
@@ -1113,8 +1113,10 @@ int avc_ca_pmt(struct firedtv *fdtv, char *msg, int length)
 	c->operand[write_pos++] = 0x00;
 	c->operand[write_pos++] = 0x00;
 
-	c->operand[7] = write_pos - 8;
-	c->operand[12] = write_pos - 13;
+	c->operand[7] = 0x82;
+	c->operand[8] = (write_pos - 10) >> 8;
+	c->operand[9] = (write_pos - 10) & 0xff;
+	c->operand[14] = write_pos - 15;
 
 	crc32_csum = crc32_be(0, &c->operand[10], c->operand[12] - 1);
 	c->operand[write_pos - 4] = (crc32_csum >> 24) & 0xff;