[RESENT] MEDIA CODA: Fix NULL ptr dereference in the encoder.

ctx->mb_err_cnt_ctrl could be NULL in case of failed initialization
(on decoders), and encoders don't use it at all.

Fixes: b2d3bef1aa78 ("media: coda: Add a V4L2 user for control error macroblocks count")
Signed-off-by: Krzysztof Halasa <khalasa@piap.pl>
Cc: stable@vger.kernel.org # 5.11+

Hi Krzysztof,

thank you for the patch.

On Mon, 2021-06-07 at 13:05 +0200, Krzysztof Halasa wrote:
> ctx->mb_err_cnt_ctrl could be NULL in case of failed initialization

> (on decoders), and encoders don't use it at all.

> 

> Fixes: b2d3bef1aa78 ("media: coda: Add a V4L2 user for control error macroblocks count")

> Signed-off-by: Krzysztof Halasa <khalasa@piap.pl>

> Cc: stable@vger.kernel.org # 5.11+

> 

> diff --git a/drivers/media/platform/coda/coda-bit.c b/drivers/media/platform/coda/coda-bit.c

> index 2f42808c43a4..26e37cbfe8dd 100644

> --- a/drivers/media/platform/coda/coda-bit.c

> +++ b/drivers/media/platform/coda/coda-bit.c

> @@ -2373,8 +2373,10 @@ static void coda_finish_decode(struct coda_ctx *ctx)

>  	if (err_mb > 0) {

>  		if (__ratelimit(&dev->mb_err_rs))

>  			coda_dbg(1, ctx, "errors in %d macroblocks\n", err_mb);

> -		v4l2_ctrl_s_ctrl(ctx->mb_err_cnt_ctrl,

> -				 v4l2_ctrl_g_ctrl(ctx->mb_err_cnt_ctrl) + err_mb);

> +		if (ctx->mb_err_cnt_ctrl)

> +			v4l2_ctrl_s_ctrl(ctx->mb_err_cnt_ctrl,

> +					 v4l2_ctrl_g_ctrl(ctx->mb_err_cnt_ctrl)

> +					 + err_mb);

>  	}

>  

>  	if (dev->devtype->product == CODA_HX4 ||


I don't think this is required though. If v4l2_ctrl_new_custom() fails
in coda_ctrls_setup(), ctx->ctrls.error is set and the function returns
-EINVAL, causing coda_open() to fail with the error message "failed to
setup coda controls". I see no way to reach coda_finish_decode() without
ctx->mb_err_cnt_ctrl being set correctly.

> diff --git a/drivers/media/platform/coda/coda-common.c b/drivers/media/platform/coda/coda-common.c

> index 96802b8f47ea..285c80f87b65 100644

> --- a/drivers/media/platform/coda/coda-common.c

> +++ b/drivers/media/platform/coda/coda-common.c

> @@ -2062,7 +2062,8 @@ static int coda_start_streaming(struct vb2_queue *q, unsigned int count)

>  	if (q_data_dst->fourcc == V4L2_PIX_FMT_JPEG)

>  		ctx->params.gop_size = 1;

>  	ctx->gopcounter = ctx->params.gop_size - 1;

> -	v4l2_ctrl_s_ctrl(ctx->mb_err_cnt_ctrl, 0);

> +	if (ctx->mb_err_cnt_ctrl)

> +		v4l2_ctrl_s_ctrl(ctx->mb_err_cnt_ctrl, 0);

>  

>  	ret = ctx->ops->start_streaming(ctx);

>  	if (ctx->inst_type == CODA_INST_DECODER) {


This is already fixed by [1] in media-tree/master.

[1] 0b276e470a4d ("media: coda: fix macroblocks count control usage")

regards
Philipp

Hi Philipp,

> I don't think this is required though.


and

> This is already fixed by [1] in media-tree/master.


Ok, thanks, sorry for the noise.
-- 
Krzysztof Hałasa

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