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author | YongSu Yoo <yongsuyoo0215@gmail.com> | 2022-08-18 13:50:27 +0100 |
---|---|---|
committer | Mauro Carvalho Chehab <mchehab@kernel.org> | 2023-05-14 06:30:16 +0100 |
commit | a4315e5be7020aac9b24a8151caf4bb85224cd0e (patch) | |
tree | 1b62cd250d222e195c0acf6ab3f36933e91e0a93 /drivers/media | |
parent | e6ad6233592593079db5c8fa592c298e51bc1356 (diff) | |
download | lwn-a4315e5be7020aac9b24a8151caf4bb85224cd0e.tar.gz lwn-a4315e5be7020aac9b24a8151caf4bb85224cd0e.zip |
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.c | 12 |
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; |