2018-12-20 08:59:36

by Kangjie Lu

Subject: [PATCH] media: drx: fix a missing check of return value

Function drxj_dap_write_reg16(), which writes data to buffer, may fail.
We need to check if it fails, and if so, we should goto error.
Otherwise, the buffer will have incorrect data.

Signed-off-by: Kangjie Lu <[email protected]>
---
drivers/media/dvb-frontends/drx39xyj/drxj.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/media/dvb-frontends/drx39xyj/drxj.c b/drivers/media/dvb-frontends/drx39xyj/drxj.c
index 551b7d65fa66..d105125bc1c3 100644
--- a/drivers/media/dvb-frontends/drx39xyj/drxj.c
+++ b/drivers/media/dvb-frontends/drx39xyj/drxj.c
@@ -2136,9 +2136,13 @@ int drxj_dap_atomic_read_write_block(struct i2c_device_addr *dev_addr,

word = ((u16) data[2 * i]);
word += (((u16) data[(2 * i) + 1]) << 8);
- drxj_dap_write_reg16(dev_addr,
+ rc = drxj_dap_write_reg16(dev_addr,
(DRXJ_HI_ATOMIC_BUF_START + i),
word, 0);
+ if (rc) {
+ pr_err("error %d\n", rc);
+ goto rw_error;
+ }
}
}

--
2.17.2 (Apple Git-113)

2019-01-07 19:58:59

by Mauro Carvalho Chehab

Subject: Re: [PATCH] media: drx: fix a missing check of return value

Em Thu, 20 Dec 2018 00:57:44 -0600
Kangjie Lu <[email protected]> escreveu:

> Function drxj_dap_write_reg16(), which writes data to buffer, may fail.
> We need to check if it fails, and if so, we should goto error.

Did you test this on a real hardware? This kind of patch has a potential
of breaking things, as, on some drivers, some writes may return error.

For example, when called on early stages, a write may fail because
the firmware was not loaded yet. So, a change like that should be
carefully tested with real hardware.

> Otherwise, the buffer will have incorrect data.
>
> Signed-off-by: Kangjie Lu <[email protected]>
> ---
> drivers/media/dvb-frontends/drx39xyj/drxj.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/media/dvb-frontends/drx39xyj/drxj.c b/drivers/media/dvb-frontends/drx39xyj/drxj.c
> index 551b7d65fa66..d105125bc1c3 100644
> --- a/drivers/media/dvb-frontends/drx39xyj/drxj.c
> +++ b/drivers/media/dvb-frontends/drx39xyj/drxj.c
> @@ -2136,9 +2136,13 @@ int drxj_dap_atomic_read_write_block(struct i2c_device_addr *dev_addr,
>
> word = ((u16) data[2 * i]);
> word += (((u16) data[(2 * i) + 1]) << 8);
> - drxj_dap_write_reg16(dev_addr,
> + rc = drxj_dap_write_reg16(dev_addr,
> (DRXJ_HI_ATOMIC_BUF_START + i),
> word, 0);
> + if (rc) {
> + pr_err("error %d\n", rc);
> + goto rw_error;
> + }
> }
> }
>



Thanks,
Mauro