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lavc/ffv1dec: fix races in accessing FFV1SliceContext.slice_damaged 

That variable is shared between frame threads in the same defective way
described in the previous commit. Fix it by adding a RefStruct-managed
arrays of flags that is propagated across frame threads in the standard
manner.

Remove now-unused FFV1Context.fsrc
This commit is contained in:
Anton Khirnov 2024-07-16 18:21:29 +02:00
parent 15bdca054f
commit 8d5efc2182
3 changed files with 45 additions and 18 deletions
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2
libavcodec/ffv1.c
View File

@ -214,6 +214,8 @@ av_cold int ff_ffv1_close(AVCodecContext *avctx)
ff_refstruct_unref(&sc->plane);
}
ff_refstruct_unref(&s->slice_damaged);
av_freep(&avctx->stats_out);
for (j = 0; j < s->quant_table_count; j++) {
av_freep(&s->initial_states[j]);

14
libavcodec/ffv1.h
View File

@ -118,7 +118,6 @@ typedef struct FFV1Context {
int64_t picture_number;
int key_frame;
ProgressFrame picture, last_picture;
struct FFV1Context *fsrc;
const AVFrame *cur_enc_frame;
int plane_count;
@ -148,6 +147,19 @@ typedef struct FFV1Context {
int num_h_slices;
FFV1SliceContext *slices;
/* RefStruct object, per-slice damage flags shared between frame threads.
*
* After a frame thread marks some slice as finished with
* ff_progress_frame_report(), the corresponding array element must not be
* accessed by this thread anymore, as from then on it is owned by the next
* thread.
*/
uint8_t *slice_damaged;
/* Frame damage flag, used to delay announcing progress, since ER is
* applied after all the slices are decoded.
* NOT shared between frame threads.
*/
uint8_t frame_damaged;
} FFV1Context;
int ff_ffv1_common_init(AVCodecContext *avctx);

47
libavcodec/ffv1dec.c
View File

@ -254,6 +254,16 @@ static int decode_slice_header(const FFV1Context *f,
return 0;
}
static void slice_set_damaged(FFV1Context *f, FFV1SliceContext *sc)
{
sc->slice_damaged = 1;
// only set this for frame threading, as for slice threading its value is
// not used and setting it would be a race
if (f->avctx->active_thread_type & FF_THREAD_FRAME)
f->frame_damaged = 1;
}
static int decode_slice(AVCodecContext *c, void *arg)
{
FFV1Context *f = c->priv_data;
@ -264,15 +274,11 @@ static int decode_slice(AVCodecContext *c, void *arg)
const int si = sc - f->slices;
GetBitContext gb;
if (f->fsrc && !(p->flags & AV_FRAME_FLAG_KEY) && f->last_picture.f)
if (!(p->flags & AV_FRAME_FLAG_KEY) && f->last_picture.f)
ff_progress_frame_await(&f->last_picture, si);
if (f->fsrc) {
const FFV1SliceContext *scsrc = &f->fsrc->slices[si];
if (!(p->flags & AV_FRAME_FLAG_KEY))
sc->slice_damaged |= scsrc->slice_damaged;
}
if (f->slice_damaged[si])
slice_set_damaged(f, sc);
sc->slice_rct_by_coef = 1;
sc->slice_rct_ry_coef = 1;
@ -282,7 +288,7 @@ static int decode_slice(AVCodecContext *c, void *arg)
return AVERROR(ENOMEM);
if (decode_slice_header(f, sc, p) < 0) {
sc->slice_x = sc->slice_y = sc->slice_height = sc->slice_width = 0;
sc->slice_damaged = 1;
slice_set_damaged(f, sc);
return AVERROR_INVALIDDATA;
}
}
@ -344,11 +350,12 @@ static int decode_slice(AVCodecContext *c, void *arg)
v = sc->c.bytestream_end - sc->c.bytestream - 2 - 5*f->ec;
if (v) {
av_log(f->avctx, AV_LOG_ERROR, "bytestream end mismatching by %d\n", v);
sc->slice_damaged = 1;
slice_set_damaged(f, sc);
}
}
ff_progress_frame_report(&f->picture, si);
if ((c->active_thread_type & FF_THREAD_FRAME) && !f->frame_damaged)
ff_progress_frame_report(&f->picture, si);
return 0;
}
@ -768,11 +775,14 @@ static int read_header(FFV1Context *f)
return AVERROR_INVALIDDATA;
}
ff_refstruct_unref(&f->slice_damaged);
f->slice_damaged = ff_refstruct_allocz(f->slice_count * sizeof(*f->slice_damaged));
if (!f->slice_damaged)
return AVERROR(ENOMEM);
for (int j = 0; j < f->slice_count; j++) {
FFV1SliceContext *sc = &f->slices[j];
sc->slice_damaged = 0;
if (f->version == 2) {
int sx = get_symbol(c, state, 0);
int sy = get_symbol(c, state, 0);
@ -857,6 +867,7 @@ static int decode_frame(AVCodecContext *avctx, AVFrame *rframe,
f->avctx = avctx;
f->frame_damaged = 0;
ff_init_range_decoder(c, buf, buf_size);
ff_build_rac_states(c, 0.05 * (1LL << 32), 256 - 8);
@ -920,6 +931,8 @@ static int decode_frame(AVCodecContext *avctx, AVFrame *rframe,
int trailer = 3 + 5*!!f->ec;
int v;
sc->slice_damaged = 0;
if (i || f->version > 2) {
if (trailer > buf_p - buf) v = INT_MAX;
else v = AV_RB24(buf_p-trailer) + trailer;
@ -943,7 +956,7 @@ static int decode_frame(AVCodecContext *avctx, AVFrame *rframe,
} else {
av_log(f->avctx, AV_LOG_ERROR, "\n");
}
sc->slice_damaged = 1;
slice_set_damaged(f, sc);
}
if (avctx->debug & FF_DEBUG_PICT_INFO) {
av_log(avctx, AV_LOG_DEBUG, "slice %d, CRC: 0x%08"PRIX32"\n", i, AV_RB32(buf_p + v - 4));
@ -988,6 +1001,8 @@ static int decode_frame(AVCodecContext *avctx, AVFrame *rframe,
avctx->pix_fmt,
sc->slice_width,
sc->slice_height);
f->slice_damaged[i] = 1;
}
}
ff_progress_frame_report(&f->picture, INT_MAX);
@ -1039,8 +1054,6 @@ static int update_thread_context(AVCodecContext *dst, const AVCodecContext *src)
FFV1SliceContext *sc = &fdst->slices[i];
const FFV1SliceContext *sc0 = &fsrc->slices[i];
sc->slice_damaged = sc0->slice_damaged;
ff_refstruct_replace(&sc->plane, sc0->plane);
if (fsrc->version < 3) {
@ -1051,12 +1064,12 @@ static int update_thread_context(AVCodecContext *dst, const AVCodecContext *src)
}
}
ff_refstruct_replace(&fdst->slice_damaged, fsrc->slice_damaged);
av_assert1(fdst->max_slice_count == fsrc->max_slice_count);
ff_progress_frame_replace(&fdst->picture, &fsrc->picture);
fdst->fsrc = fsrc;
return 0;
}
#endif