Re: [PATCH v2 7/8] cedrus: Use vb2_find_buffer

[Ezequiel Garcia]

Hi Jernej,

On Sat, Jul 16, 2022 at 9:36 AM Jernej Škrabec <jernej.skrabec@xxxxxxxxx> wrote:
>
> Dne petek, 15. julij 2022 ob 13:48:34 CEST je Ezequiel Garcia napisal(a):
> > Hi Nicolas,
> >
> > Thanks a lot for the test and the bug report.
> >
> > On Thu, Jul 14, 2022 at 4:26 PM Nicolas Dufresne <nicolas@xxxxxxxxxxxx>
> wrote:
> > > Hi Ezequiel,
> > >
> > > I started testing with these patches and found some NULL dreferences, see
> > > my comment inline...
> > >
> > > Le lundi 11 juillet 2022 à 18:11 -0300, Ezequiel Garcia a écrit :
> > > > Use the newly introduced vb2_find_buffer API to get a vb2_buffer
> > > > given a buffer timestamp.
> > > >
> > > > Cc: Maxime Ripard <mripard@xxxxxxxxxx>
> > > > Cc: Paul Kocialkowski <paul.kocialkowski@xxxxxxxxxxx>
> > > > Cc: Jernej Skrabec <jernej.skrabec@xxxxxxxxx>
> > > > Signed-off-by: Ezequiel Garcia <ezequiel@xxxxxxxxxxxxxxxxxxxx>
> > > > Acked-by: Tomasz Figa <tfiga@xxxxxxxxxxxx>
> > > > ---
> > > >
> > > >  drivers/staging/media/sunxi/cedrus/cedrus.h   | 24 ++++++-----
> > > >  .../staging/media/sunxi/cedrus/cedrus_h264.c  | 16 +++----
> > > >  .../staging/media/sunxi/cedrus/cedrus_h265.c  | 16 +++----
> > > >  .../staging/media/sunxi/cedrus/cedrus_mpeg2.c | 28 ++++--------
> > > >  .../staging/media/sunxi/cedrus/cedrus_vp8.c   | 43 ++++---------------
> > > >  5 files changed, 46 insertions(+), 81 deletions(-)
> > > >
> > > > diff --git a/drivers/staging/media/sunxi/cedrus/cedrus.h
> > > > b/drivers/staging/media/sunxi/cedrus/cedrus.h index
> > > > 3bc094eb497f..c054dbe3d3bc 100644
> > > > --- a/drivers/staging/media/sunxi/cedrus/cedrus.h
> > > > +++ b/drivers/staging/media/sunxi/cedrus/cedrus.h
> > > > @@ -233,19 +233,23 @@ static inline dma_addr_t cedrus_buf_addr(struct
> > > > vb2_buffer *buf,> >
> > > >  }
> > > >
> > > >  static inline dma_addr_t cedrus_dst_buf_addr(struct cedrus_ctx *ctx,
> > > >
> > > > -                                          int index, unsigned int
> > > > plane)
> > > > +                                          struct vb2_buffer *buf,
> > > > +                                          unsigned int plane)
> > > >
> > > >  {
> > > >
> > > > -     struct vb2_buffer *buf = NULL;
> > > > -     struct vb2_queue *vq;
> > > > -
> > > > -     if (index < 0)
> > > > -             return 0;
> > > > +     return buf ? cedrus_buf_addr(buf, &ctx->dst_fmt, plane) : 0;
> > > > +}
> > > >
> > > > -     vq = v4l2_m2m_get_vq(ctx->fh.m2m_ctx,
> > > > V4L2_BUF_TYPE_VIDEO_CAPTURE);
> > > > -     if (vq)
> > > > -             buf = vb2_get_buffer(vq, index);
> > > > +static inline void cedrus_write_ref_buf_addr(struct cedrus_ctx *ctx,
> > > > +                                          struct vb2_queue *q,
> > > > +                                          u64 timestamp,
> > > > +                                          u32 luma_reg,
> > > > +                                          u32 chroma_reg)
> > > > +{
> > > > +       struct cedrus_dev *dev = ctx->dev;
> > > > +       struct vb2_buffer *buf = vb2_find_buffer(q, timestamp);
> > > >
> > > > -     return buf ? cedrus_buf_addr(buf, &ctx->dst_fmt, plane) : 0;
> > > > +       cedrus_write(dev, luma_reg, cedrus_dst_buf_addr(ctx, buf, 0));
> > > > +       cedrus_write(dev, chroma_reg, cedrus_dst_buf_addr(ctx, buf, 1));
> > > >
> > > >  }
> > > >
> > > >  static inline struct cedrus_buffer *
> > > >
> > > > diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_h264.c
> > > > b/drivers/staging/media/sunxi/cedrus/cedrus_h264.c index
> > > > d8fb93035470..0559efeac125 100644
> > > > --- a/drivers/staging/media/sunxi/cedrus/cedrus_h264.c
> > > > +++ b/drivers/staging/media/sunxi/cedrus/cedrus_h264.c
> > > > @@ -111,16 +111,16 @@ static void cedrus_write_frame_list(struct
> > > > cedrus_ctx *ctx,> >
> > > >       for (i = 0; i < ARRAY_SIZE(decode->dpb); i++) {
> > > >
> > > >               const struct v4l2_h264_dpb_entry *dpb = &decode->dpb[i];
> > > >               struct cedrus_buffer *cedrus_buf;
> > > >
> > > > -             int buf_idx;
> > > > +             struct vb2_buffer *buf;
> > > >
> > > >               if (!(dpb->flags & V4L2_H264_DPB_ENTRY_FLAG_VALID))
> > > >
> > > >                       continue;
> > > >
> > > > -             buf_idx = vb2_find_timestamp(cap_q, dpb->reference_ts, 0);
> > > > -             if (buf_idx < 0)
> > > > +             buf = vb2_find_buffer(cap_q, dpb->reference_ts);
> > > > +             if (!buf)
> > > >
> > > >                       continue;
> > > >
> > > > -             cedrus_buf = vb2_to_cedrus_buffer(cap_q->bufs[buf_idx]);
> > > > +             cedrus_buf = vb2_to_cedrus_buffer(buf);
> > > >
> > > >               position = cedrus_buf->codec.h264.position;
> > > >               used_dpbs |= BIT(position);
> > > >
> > > > @@ -186,7 +186,7 @@ static void _cedrus_write_ref_list(struct cedrus_ctx
> > > > *ctx,> >
> > > >               const struct v4l2_h264_dpb_entry *dpb;
> > > >               const struct cedrus_buffer *cedrus_buf;
> > > >               unsigned int position;
> > > >
> > > > -             int buf_idx;
> > > > +             struct vb2_buffer *buf;
> > > >
> > > >               u8 dpb_idx;
> > > >
> > > >               dpb_idx = ref_list[i].index;
> > > >
> > > > @@ -195,11 +195,11 @@ static void _cedrus_write_ref_list(struct
> > > > cedrus_ctx *ctx,> >
> > > >               if (!(dpb->flags & V4L2_H264_DPB_ENTRY_FLAG_ACTIVE))
> > > >
> > > >                       continue;
> > > >
> > > > -             buf_idx = vb2_find_timestamp(cap_q, dpb->reference_ts, 0);
> > > > -             if (buf_idx < 0)
> > > > +             buf = vb2_find_buffer(cap_q, dpb->reference_ts);
> > > > +             if (!buf)
> > > >
> > > >                       continue;
> > > >
> > > > -             cedrus_buf = vb2_to_cedrus_buffer(cap_q->bufs[buf_idx]);
> > > > +             cedrus_buf = vb2_to_cedrus_buffer(buf);
> > > >
> > > >               position = cedrus_buf->codec.h264.position;
> > > >
> > > >               sram_array[i] |= position << 1;
> > > >
> > > > diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_h265.c
> > > > b/drivers/staging/media/sunxi/cedrus/cedrus_h265.c index
> > > > 44f385be9f6c..60cc13e4d0a9 100644
> > > > --- a/drivers/staging/media/sunxi/cedrus/cedrus_h265.c
> > > > +++ b/drivers/staging/media/sunxi/cedrus/cedrus_h265.c
> > > > @@ -102,14 +102,14 @@ static void
> > > > cedrus_h265_frame_info_write_single(struct cedrus_ctx *ctx,> >
> > > >                                               unsigned int index,
> > > >                                               bool field_pic,
> > > >                                               u32 pic_order_cnt[],
> > > >
> > > > -                                             int buffer_index)
> > > > +                                             struct vb2_buffer *buf)
> > > >
> > > >  {
> > > >
> > > >       struct cedrus_dev *dev = ctx->dev;
> > > >
> > > > -     dma_addr_t dst_luma_addr = cedrus_dst_buf_addr(ctx, buffer_index,
> > > > 0);
> > > > -     dma_addr_t dst_chroma_addr = cedrus_dst_buf_addr(ctx,
> > > > buffer_index, 1); +     dma_addr_t dst_luma_addr =
> > > > cedrus_dst_buf_addr(ctx, buf, 0); +     dma_addr_t dst_chroma_addr =
> > > > cedrus_dst_buf_addr(ctx, buf, 1);> >
> > > >       dma_addr_t mv_col_buf_addr[2] = {
> > > >
> > > > -             cedrus_h265_frame_info_mv_col_buf_addr(ctx, buffer_index,
> > > > 0),
> > > > -             cedrus_h265_frame_info_mv_col_buf_addr(ctx, buffer_index,
> > > > +             cedrus_h265_frame_info_mv_col_buf_addr(ctx, buf->index,
> > > > 0),
> > > > +             cedrus_h265_frame_info_mv_col_buf_addr(ctx, buf->index,
> > > >
> > > >                                                      field_pic ? 1 : 0)
> > >
> > > Previously, -1 would be passed to
> > > cedrus_h265_frame_info_mv_col_buf_addr(),
> > > which would not find a buffer at that index, and would return 0. Now the
> > > code will crash with a NULL pointer deref.
> >
> > Is it really correct to pass -1 to cedrus_h265_frame_info_mv_col_buf_addr?
> > It seems it get casted into an unsigned type and then used to calculate
> > an address for DMA.
>
> I totally agree that this is a latent bug and it should be fixed. H264 checks
> for negative value, but not HEVC. Current code just makes out of bounds read,
> which is tolerated, but yours causes NULL pointer dereference, which is not.
>
> I suggest that following check is added in cedrus_h265_frame_info_write_dpb():
>
> if (buffer_index < 0)
>  continue;
>

Seems reasonable.

> I can send it as a fix so it gets backported and you update this patch so above
> if is changed to NULL pointer check.
>

Yes, I like this approach.

> Do you all agree? Nicolas, do you prefer to send such patch, since you're first
> who noticed something odd with the code?
>

Hans' last PR dropped the cedrus patch, and left vb2_find_timestamp
for the time being (for 5.20). I like the proposal of sending a fix that can
be backported. I can re-work the rest of this series on top.

Thanks,
Ezequiel

> Best regards,
> Jernej
>
> >
> > static inline dma_addr_t
> > cedrus_h265_frame_info_mv_col_buf_addr(struct cedrus_ctx *ctx,
> >                                        unsigned int index, unsigned int
> > field) {
> >         return ctx->codec.h265.mv_col_buf_addr + index *
> >                ctx->codec.h265.mv_col_buf_unit_size +
> >                field * ctx->codec.h265.mv_col_buf_unit_size / 2;
> > }
> >
> > Fixing the driver to go back to the previous behavior is trivial,
> > but this looks odd.
> >
> > Jernej, Paul, any thoughts?
> >
> > Thanks,
> > Ezequiel
> >
> > > >       };
> > > >       u32 offset = VE_DEC_H265_SRAM_OFFSET_FRAME_INFO +
> > > >
> > > > @@ -141,7 +141,7 @@ static void cedrus_h265_frame_info_write_dpb(struct
> > > > cedrus_ctx *ctx,> >
> > > >       unsigned int i;
> > > >
> > > >       for (i = 0; i < num_active_dpb_entries; i++) {
> > > >
> > > > -             int buffer_index = vb2_find_timestamp(vq,
> > > > dpb[i].timestamp, 0); +             struct vb2_buffer *buf =
> > > > vb2_find_buffer(vq, dpb[i].timestamp);> >
> > > >               u32 pic_order_cnt[2] = {
> > > >
> > > >                       dpb[i].pic_order_cnt[0],
> > > >                       dpb[i].pic_order_cnt[1]
> > > >
> > > > @@ -149,7 +149,7 @@ static void cedrus_h265_frame_info_write_dpb(struct
> > > > cedrus_ctx *ctx,> >
> > > >               cedrus_h265_frame_info_write_single(ctx, i,
> > > >               dpb[i].field_pic,
> > > >
> > > >                                                   pic_order_cnt,
> > > >
> > > > -                                                 buffer_index);
> > > > +                                                 buf);
> > > >
> > > >       }
> > > >
> > > >  }
> > > >
> > > > @@ -616,7 +616,7 @@ static void cedrus_h265_setup(struct cedrus_ctx
> > > > *ctx,
> > > >
> > > >       cedrus_h265_frame_info_write_single(ctx, output_pic_list_index,
> > > >
> > > >                                           slice_params->pic_struct != 0,
> > > >                                           pic_order_cnt,
> > > >
> > > > -                                         run->dst->vb2_buf.index);
> > > > +                                         &run->dst->vb2_buf);
> > > >
> > > >       cedrus_write(dev, VE_DEC_H265_OUTPUT_FRAME_IDX,
> > > >       output_pic_list_index);
> > > >
> > > > diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_mpeg2.c
> > > > b/drivers/staging/media/sunxi/cedrus/cedrus_mpeg2.c index
> > > > 5dad2f296c6d..22d6cae9a710 100644
> > > > --- a/drivers/staging/media/sunxi/cedrus/cedrus_mpeg2.c
> > > > +++ b/drivers/staging/media/sunxi/cedrus/cedrus_mpeg2.c
> > > > @@ -54,13 +54,9 @@ static void cedrus_mpeg2_setup(struct cedrus_ctx
> > > > *ctx, struct cedrus_run *run)> >
> > > >       const struct v4l2_ctrl_mpeg2_picture *pic;
> > > >       const struct v4l2_ctrl_mpeg2_quantisation *quantisation;
> > > >       dma_addr_t src_buf_addr, dst_luma_addr, dst_chroma_addr;
> > > >
> > > > -     dma_addr_t fwd_luma_addr, fwd_chroma_addr;
> > > > -     dma_addr_t bwd_luma_addr, bwd_chroma_addr;
> > > >
> > > >       struct cedrus_dev *dev = ctx->dev;
> > > >       struct vb2_queue *vq;
> > > >       const u8 *matrix;
> > > >
> > > > -     int forward_idx;
> > > > -     int backward_idx;
> > > >
> > > >       unsigned int i;
> > > >       u32 reg;
> > > >
> > > > @@ -123,27 +119,19 @@ static void cedrus_mpeg2_setup(struct cedrus_ctx
> > > > *ctx, struct cedrus_run *run)> >
> > > >       cedrus_write(dev, VE_DEC_MPEG_PICBOUNDSIZE, reg);
> > > >
> > > >       /* Forward and backward prediction reference buffers. */
> > > >
> > > > -
> > > >
> > > >       vq = v4l2_m2m_get_vq(ctx->fh.m2m_ctx,
> > > >       V4L2_BUF_TYPE_VIDEO_CAPTURE);
> > > >
> > > > -     forward_idx = vb2_find_timestamp(vq, pic->forward_ref_ts, 0);
> > > > -     fwd_luma_addr = cedrus_dst_buf_addr(ctx, forward_idx, 0);
> > > > -     fwd_chroma_addr = cedrus_dst_buf_addr(ctx, forward_idx, 1);
> > > > -
> > > > -     cedrus_write(dev, VE_DEC_MPEG_FWD_REF_LUMA_ADDR, fwd_luma_addr);
> > > > -     cedrus_write(dev, VE_DEC_MPEG_FWD_REF_CHROMA_ADDR,
> > > > fwd_chroma_addr);
> > > > -
> > > > -     backward_idx = vb2_find_timestamp(vq, pic->backward_ref_ts, 0);
> > > > -     bwd_luma_addr = cedrus_dst_buf_addr(ctx, backward_idx, 0);
> > > > -     bwd_chroma_addr = cedrus_dst_buf_addr(ctx, backward_idx, 1);
> > > > -
> > > > -     cedrus_write(dev, VE_DEC_MPEG_BWD_REF_LUMA_ADDR, bwd_luma_addr);
> > > > -     cedrus_write(dev, VE_DEC_MPEG_BWD_REF_CHROMA_ADDR,
> > > > bwd_chroma_addr);
> > > > +     cedrus_write_ref_buf_addr(ctx, vq, pic->forward_ref_ts,
> > > > +                               VE_DEC_MPEG_FWD_REF_LUMA_ADDR,
> > > > +                               VE_DEC_MPEG_FWD_REF_CHROMA_ADDR);
> > > > +     cedrus_write_ref_buf_addr(ctx, vq, pic->backward_ref_ts,
> > > > +                               VE_DEC_MPEG_BWD_REF_LUMA_ADDR,
> > > > +                               VE_DEC_MPEG_BWD_REF_CHROMA_ADDR);
> > > >
> > > >       /* Destination luma and chroma buffers. */
> > > >
> > > > -     dst_luma_addr = cedrus_dst_buf_addr(ctx, run->dst->vb2_buf.index,
> > > > 0);
> > > > -     dst_chroma_addr = cedrus_dst_buf_addr(ctx,
> > > > run->dst->vb2_buf.index, 1); +     dst_luma_addr =
> > > > cedrus_dst_buf_addr(ctx, &run->dst->vb2_buf, 0); +     dst_chroma_addr
> > > > = cedrus_dst_buf_addr(ctx, &run->dst->vb2_buf, 1);> >
> > > >       cedrus_write(dev, VE_DEC_MPEG_REC_LUMA, dst_luma_addr);
> > > >       cedrus_write(dev, VE_DEC_MPEG_REC_CHROMA, dst_chroma_addr);
> > > >
> > > > diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_vp8.c
> > > > b/drivers/staging/media/sunxi/cedrus/cedrus_vp8.c index
> > > > f4016684b32d..196cf692186d 100644
> > > > --- a/drivers/staging/media/sunxi/cedrus/cedrus_vp8.c
> > > > +++ b/drivers/staging/media/sunxi/cedrus/cedrus_vp8.c
> > > > @@ -661,7 +661,6 @@ static void cedrus_vp8_setup(struct cedrus_ctx *ctx,
> > > >
> > > >       dma_addr_t luma_addr, chroma_addr;
> > > >       dma_addr_t src_buf_addr;
> > > >       int header_size;
> > > >
> > > > -     int qindex;
> > > >
> > > >       u32 reg;
> > > >
> > > >       cedrus_engine_enable(ctx, CEDRUS_CODEC_VP8);
> > > >
> > > > @@ -805,43 +804,17 @@ static void cedrus_vp8_setup(struct cedrus_ctx
> > > > *ctx,
> > > >
> > > >       reg |= VE_VP8_LF_DELTA0(slice->lf.mb_mode_delta[0]);
> > > >       cedrus_write(dev, VE_VP8_MODE_LF_DELTA, reg);
> > > >
> > > > -     luma_addr = cedrus_dst_buf_addr(ctx, run->dst->vb2_buf.index, 0);
> > > > -     chroma_addr = cedrus_dst_buf_addr(ctx, run->dst->vb2_buf.index,
> > > > 1);
> > > > +     luma_addr = cedrus_dst_buf_addr(ctx, &run->dst->vb2_buf, 0);
> > > > +     chroma_addr = cedrus_dst_buf_addr(ctx, &run->dst->vb2_buf, 1);
> > > >
> > > >       cedrus_write(dev, VE_VP8_REC_LUMA, luma_addr);
> > > >       cedrus_write(dev, VE_VP8_REC_CHROMA, chroma_addr);
> > > >
> > > > -     qindex = vb2_find_timestamp(cap_q, slice->last_frame_ts, 0);
> > > > -     if (qindex >= 0) {
> > > > -             luma_addr = cedrus_dst_buf_addr(ctx, qindex, 0);
> > > > -             chroma_addr = cedrus_dst_buf_addr(ctx, qindex, 1);
> > > > -             cedrus_write(dev, VE_VP8_FWD_LUMA, luma_addr);
> > > > -             cedrus_write(dev, VE_VP8_FWD_CHROMA, chroma_addr);
> > > > -     } else {
> > > > -             cedrus_write(dev, VE_VP8_FWD_LUMA, 0);
> > > > -             cedrus_write(dev, VE_VP8_FWD_CHROMA, 0);
> > > > -     }
> > > > -
> > > > -     qindex = vb2_find_timestamp(cap_q, slice->golden_frame_ts, 0);
> > > > -     if (qindex >= 0) {
> > > > -             luma_addr = cedrus_dst_buf_addr(ctx, qindex, 0);
> > > > -             chroma_addr = cedrus_dst_buf_addr(ctx, qindex, 1);
> > > > -             cedrus_write(dev, VE_VP8_BWD_LUMA, luma_addr);
> > > > -             cedrus_write(dev, VE_VP8_BWD_CHROMA, chroma_addr);
> > > > -     } else {
> > > > -             cedrus_write(dev, VE_VP8_BWD_LUMA, 0);
> > > > -             cedrus_write(dev, VE_VP8_BWD_CHROMA, 0);
> > > > -     }
> > > > -
> > > > -     qindex = vb2_find_timestamp(cap_q, slice->alt_frame_ts, 0);
> > > > -     if (qindex >= 0) {
> > > > -             luma_addr = cedrus_dst_buf_addr(ctx, qindex, 0);
> > > > -             chroma_addr = cedrus_dst_buf_addr(ctx, qindex, 1);
> > > > -             cedrus_write(dev, VE_VP8_ALT_LUMA, luma_addr);
> > > > -             cedrus_write(dev, VE_VP8_ALT_CHROMA, chroma_addr);
> > > > -     } else {
> > > > -             cedrus_write(dev, VE_VP8_ALT_LUMA, 0);
> > > > -             cedrus_write(dev, VE_VP8_ALT_CHROMA, 0);
> > > > -     }
> > > > +     cedrus_write_ref_buf_addr(ctx, cap_q, slice->last_frame_ts,
> > > > +                               VE_VP8_FWD_LUMA, VE_VP8_FWD_CHROMA);
> > > > +     cedrus_write_ref_buf_addr(ctx, cap_q, slice->golden_frame_ts,
> > > > +                               VE_VP8_BWD_LUMA, VE_VP8_BWD_CHROMA);
> > > > +     cedrus_write_ref_buf_addr(ctx, cap_q, slice->alt_frame_ts,
> > > > +                               VE_VP8_ALT_LUMA, VE_VP8_ALT_CHROMA);
> > > >
> > > >       cedrus_write(dev, VE_H264_CTRL, VE_H264_CTRL_VP8 |
> > > >
> > > >                    VE_H264_CTRL_DECODE_ERR_INT |
>
>
>
>