linux-kernel - Re: [PATCH v2] media: meson: vdec: potential dereference of null pointer

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Message-ID: <03dbdbe8-ea08-ef62-c09d-67b3baab6401@xs4all.nl>
Date:   Tue, 11 Jan 2022 10:21:59 +0100
From:   Hans Verkuil <hverkuil@...all.nl>
To:     Jiasheng Jiang <jiasheng@...as.ac.cn>, narmstrong@...libre.com,
        mchehab@...nel.org, gregkh@...uxfoundation.org,
        khilman@...libre.com, jbrunet@...libre.com,
        martin.blumenstingl@...glemail.com, p.zabel@...gutronix.de
Cc:     linux-media@...r.kernel.org, linux-amlogic@...ts.infradead.org,
        linux-staging@...ts.linux.dev,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] media: meson: vdec: potential dereference of null
 pointer

On 10/12/2021 02:56, Jiasheng Jiang wrote:
> The return value of kzalloc() needs to be checked.
> To avoid use of null pointer in case of the failure of alloc.

Same issue as with Zhou's patch: this is almost identical to Neil's patch,
but without any mention of his name.

I very much prefer it if Neil just posts his patch so I can pick that up.

Regards,

	Hans

> 
> Fixes: 876f123b8956 ("media: meson: vdec: bring up to compliance")
> Signed-off-by: Jiasheng Jiang <jiasheng@...as.ac.cn>
> ---
> Changelog:
> 
> v1 -> v2
> 
> *Change 1. Change the return type of amvdec_add_ts from void to int.
> *Change 2. Return -ENOMEN if alloc fail and return 0 if not.
> *Change 3. Modify the caller to deal with the error.
> ---
>  drivers/staging/media/meson/vdec/esparser.c     | 6 +++++-
>  drivers/staging/media/meson/vdec/vdec_helpers.c | 5 ++++-
>  drivers/staging/media/meson/vdec/vdec_helpers.h | 2 +-
>  3 files changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/staging/media/meson/vdec/esparser.c b/drivers/staging/media/meson/vdec/esparser.c
> index db7022707ff8..7e78288cc551 100644
> --- a/drivers/staging/media/meson/vdec/esparser.c
> +++ b/drivers/staging/media/meson/vdec/esparser.c
> @@ -328,9 +328,13 @@ esparser_queue(struct amvdec_session *sess, struct vb2_v4l2_buffer *vbuf)
>  
>  	offset = esparser_get_offset(sess);
>  
> -	amvdec_add_ts(sess, vb->timestamp, vbuf->timecode, offset, vbuf->flags);
> +	ret = amvdec_add_ts(sess, vb->timestamp, vbuf->timecode, offset, vbuf->flags);
>  	dev_dbg(core->dev, "esparser: ts = %llu pld_size = %u offset = %08X flags = %08X\n",
>  		vb->timestamp, payload_size, offset, vbuf->flags);
> +	if (ret) {
> +		v4l2_m2m_buf_done(vbuf, VB2_BUF_STATE_ERROR);
> +		return ret;
> +	}
>  
>  	vbuf->flags = 0;
>  	vbuf->field = V4L2_FIELD_NONE;
> diff --git a/drivers/staging/media/meson/vdec/vdec_helpers.c b/drivers/staging/media/meson/vdec/vdec_helpers.c
> index 7f07a9175815..972a1d1a12a5 100644
> --- a/drivers/staging/media/meson/vdec/vdec_helpers.c
> +++ b/drivers/staging/media/meson/vdec/vdec_helpers.c
> @@ -227,13 +227,15 @@ int amvdec_set_canvases(struct amvdec_session *sess,
>  }
>  EXPORT_SYMBOL_GPL(amvdec_set_canvases);
>  
> -void amvdec_add_ts(struct amvdec_session *sess, u64 ts,
> +int amvdec_add_ts(struct amvdec_session *sess, u64 ts,
> +		  struct v4l2_timecode tc, u32 offset, u32 vbuf_flags)
>  {
>  	struct amvdec_timestamp *new_ts;
>  	unsigned long flags;
>  
>  	new_ts = kzalloc(sizeof(*new_ts), GFP_KERNEL);
> +	if (!new_ts)
> +		return -ENOMEM;
>  	new_ts->ts = ts;
>  	new_ts->tc = tc;
>  	new_ts->offset = offset;
> @@ -242,6 +244,7 @@ void amvdec_add_ts(struct amvdec_session *sess, u64 ts,
>  	spin_lock_irqsave(&sess->ts_spinlock, flags);
>  	list_add_tail(&new_ts->list, &sess->timestamps);
>  	spin_unlock_irqrestore(&sess->ts_spinlock, flags);
> +	return 0;
>  }
>  EXPORT_SYMBOL_GPL(amvdec_add_ts);
>  
> diff --git a/drivers/staging/media/meson/vdec/vdec_helpers.h b/drivers/staging/media/meson/vdec/vdec_helpers.h
> index cfaed52ab526..1bcb697290de 100644
> --- a/drivers/staging/media/meson/vdec/vdec_helpers.h
> +++ b/drivers/staging/media/meson/vdec/vdec_helpers.h
> @@ -55,7 +55,7 @@ void amvdec_dst_buf_done_offset(struct amvdec_session *sess,
>   * @offset: offset in the VIFIFO where the associated packet was written
>   * @flags the vb2_v4l2_buffer flags
>   */
> -void amvdec_add_ts(struct amvdec_session *sess, u64 ts,
> +int amvdec_add_ts(struct amvdec_session *sess, u64 ts,
> +		  struct v4l2_timecode tc, u32 offset, u32 flags);
>  void amvdec_remove_ts(struct amvdec_session *sess, u64 ts);
>