Hi Philipp,

On 02/08/2018 12:01 PM, Hans Verkuil wrote:
On 02/08/2018 08:27 PM, Steve Longerbeam wrote:

On 02/08/2018 06:47 AM, Philipp Zabel wrote:
If no imx_media_pixfmt is found for a given mbus format code,
we shouldn't crash. Return -EINVAL for any index.
Hi Philipp,

If imx_media_find_mbus_format() returns NULL at that location, it means
the current format has an invalid pixel code. It's not possible for an
format to have an invalid code, so it must be a TRY format with an
(zero) code. Which makes sense if enum_mbus_code(TRY) pad op is called
set_fmt(TRY), at the sink pad, was *ever* called. Am I right?

It looks there is another location where this could possibly happen, in
In that case it would happen if set_fmt(TRY) is called on a source pad,
set_fmt(TRY) was ever called at the sink pad. That's a weird corner case
it's not clear what a set_fmt(TRY) at the source pads should choose for
code if there was never a set_fmt(TRY) at the sink pad.

But perhaps the following should be added to this patch as well. It
makes the
assumption that the TRY code at the sink pad is the same as the default
active code set from csi_registered().

Or maybe I should ask the question, what should drivers do in set_fmt(TRY)
at their source pads, if there was no prior set_fmt(TRY) at their sink pads?
Drivers can set the initial TRY value by implementing the init_cfg pad op.
See e.g. drivers/media/platform/vimc/vimc-sensor.c.

I *think* by implementing init_cfg in the CSI, it will prevent the
NULL deref in csi_enum_mbus_code(). However I think this patch
is a good idea in any case.


Signed-off-by: Philipp Zabel <p.za...@pengutronix.de>
   drivers/staging/media/imx/imx-media-csi.c | 4 ++++
   1 file changed, 4 insertions(+)

diff --git a/drivers/staging/media/imx/imx-media-csi.c 
index eb7be5093a9d..89903f267d60 100644
--- a/drivers/staging/media/imx/imx-media-csi.c
+++ b/drivers/staging/media/imx/imx-media-csi.c
@@ -1138,6 +1138,10 @@ static int csi_enum_mbus_code(struct v4l2_subdev *sd,
infmt = __csi_get_fmt(priv, cfg, CSI_SINK_PAD, code->which);
        incc = imx_media_find_mbus_format(infmt->code, CS_SEL_ANY, true);
+       if (!incc) {
+               ret = -EINVAL;
+               goto out;
+       }
switch (code->pad) {
        case CSI_SINK_PAD:

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