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authorYongSu Yoo <yongsuyoo0215@gmail.com>2022-08-18 13:50:27 +0100
committerMauro Carvalho Chehab <mchehab@kernel.org>2023-05-14 06:30:16 +0100
commita4315e5be7020aac9b24a8151caf4bb85224cd0e (patch)
tree1b62cd250d222e195c0acf6ab3f36933e91e0a93 /drivers/media
parente6ad6233592593079db5c8fa592c298e51bc1356 (diff)
media: dvb_ca_en50221: fix a size write bug
The function of "dvb_ca_en50221_write_data" at source/drivers/media /dvb-core/dvb_ca_en50221.c is used for two cases. The first case is for writing APDU data in the function of "dvb_ca_en50221_io_write" at source/drivers/media/dvb-core/ dvb_ca_en50221.c. The second case is for writing the host link buf size on the Command Register in the function of "dvb_ca_en50221_link_init" at source/drivers/media/dvb-core/dvb_ca_en50221.c. In the second case, there exists a bug like following. In the function of the "dvb_ca_en50221_link_init", after a TV host calculates the host link buf_size, the TV host writes the calculated host link buf_size on the Size Register. Accroding to the en50221 Spec (the page 60 of https://dvb.org/wp-content/uploads/2020/02/En50221.V1.pdf), before this writing operation, the "SW(CMDREG_SW)" flag in the Command Register should be set. We can see this setting operation in the function of the "dvb_ca_en50221_link_init" like below. ... if ((ret = ca->pub->write_cam_control(ca->pub, slot, CTRLIF_COMMAND, IRQEN | CMDREG_SW)) != 0) return ret; ... But, after that, the real writing operation is implemented using the function of the "dvb_ca_en50221_write_data" in the function of "dvb_ca_en50221_link_init", and the "dvb_ca_en50221_write_data" includes the function of "ca->pub->write_cam_control", and the function of the "ca->pub->write_cam_control" in the function of the "dvb_ca_en50221_wrte_data" does not include "CMDREG_SW" flag like below. ... if ((status = ca->pub->write_cam_control(ca->pub, slot, CTRLIF_COMMAND, IRQEN | CMDREG_HC)) != 0) ... In the above source code, we can see only the "IRQEN | CMDREG_HC", but we cannot see the "CMDREG_SW". The "CMDREG_SW" flag which was set in the function of the "dvb_ca_en50221_link_init" was rollbacked by the follwoing function of the "dvb_ca_en50221_write_data". This is a bug. and this bug causes that the calculated host link buf_size is not properly written in the CI module. Through this patch, we fix this bug. Link: https://lore.kernel.org/linux-media/20220818125027.1131-1-yongsuyoo0215@gmail.com Signed-off-by: YongSu Yoo <yongsuyoo0215@gmail.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Diffstat (limited to 'drivers/media')
-rw-r--r--drivers/media/dvb-core/dvb_ca_en50221.c12
1 files changed, 7 insertions, 5 deletions
diff --git a/drivers/media/dvb-core/dvb_ca_en50221.c b/drivers/media/dvb-core/dvb_ca_en50221.c
index c2d2792227f8..b6ca29dfb184 100644
--- a/drivers/media/dvb-core/dvb_ca_en50221.c
+++ b/drivers/media/dvb-core/dvb_ca_en50221.c
@@ -187,7 +187,7 @@ static void dvb_ca_en50221_thread_wakeup(struct dvb_ca_private *ca);
static int dvb_ca_en50221_read_data(struct dvb_ca_private *ca, int slot,
u8 *ebuf, int ecount);
static int dvb_ca_en50221_write_data(struct dvb_ca_private *ca, int slot,
- u8 *ebuf, int ecount);
+ u8 *ebuf, int ecount, int size_write_flag);
/**
* findstr - Safely find needle in haystack.
@@ -370,7 +370,7 @@ static int dvb_ca_en50221_link_init(struct dvb_ca_private *ca, int slot)
ret = dvb_ca_en50221_wait_if_status(ca, slot, STATUSREG_FR, HZ / 10);
if (ret)
return ret;
- ret = dvb_ca_en50221_write_data(ca, slot, buf, 2);
+ ret = dvb_ca_en50221_write_data(ca, slot, buf, 2, CMDREG_SW);
if (ret != 2)
return -EIO;
ret = ca->pub->write_cam_control(ca->pub, slot, CTRLIF_COMMAND, IRQEN);
@@ -778,11 +778,13 @@ exit:
* @buf: The data in this buffer is treated as a complete link-level packet to
* be written.
* @bytes_write: Size of ebuf.
+ * @size_write_flag: A flag on Command Register which says whether the link size
+ * information will be writen or not.
*
* return: Number of bytes written, or < 0 on error.
*/
static int dvb_ca_en50221_write_data(struct dvb_ca_private *ca, int slot,
- u8 *buf, int bytes_write)
+ u8 *buf, int bytes_write, int size_write_flag)
{
struct dvb_ca_slot *sl = &ca->slot_info[slot];
int status;
@@ -817,7 +819,7 @@ static int dvb_ca_en50221_write_data(struct dvb_ca_private *ca, int slot,
/* OK, set HC bit */
status = ca->pub->write_cam_control(ca->pub, slot, CTRLIF_COMMAND,
- IRQEN | CMDREG_HC);
+ IRQEN | CMDREG_HC | size_write_flag);
if (status)
goto exit;
@@ -1508,7 +1510,7 @@ static ssize_t dvb_ca_en50221_io_write(struct file *file,
mutex_lock(&sl->slot_lock);
status = dvb_ca_en50221_write_data(ca, slot, fragbuf,
- fraglen + 2);
+ fraglen + 2, 0);
mutex_unlock(&sl->slot_lock);
if (status == (fraglen + 2)) {
written = 1;