On Wed, Sep 06, 2023 at 10:19:27PM +0000, Paul B Mahol wrote: > ffmpeg | branch: master | Paul B Mahol | Mon Aug 28 12:20:15 2023 +0200| [8b7391cb5ff94ce94612fda69392a95d7ab1ffd0] | committer: Paul B Mahol > > avcodec/magicyuv: add vlc multi support > > Gives nice speed boost, depending on encoded content it goes from > 30% to 60% faster. > > > http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=8b7391cb5ff94ce94612fda69392a95d7ab1ffd0 > --- > > libavcodec/magicyuv.c | 65 +++++++++++++++++++++++++++------------------------ > 1 file changed, 34 insertions(+), 31 deletions(-) > > diff --git a/libavcodec/magicyuv.c b/libavcodec/magicyuv.c > index 7898cd5be4..bbaf14d0e0 100644 > --- a/libavcodec/magicyuv.c > +++ b/libavcodec/magicyuv.c > @@ -34,6 +34,8 @@ > #include "lossless_videodsp.h" > #include "thread.h" > > +#define VLC_BITS 12 > + > typedef struct Slice { > uint32_t start; > uint32_t size; > @@ -67,13 +69,14 @@ typedef struct MagicYUVContext { > Slice *slices[4]; // slice bitstream positions for each plane > unsigned int slices_size[4]; // slice sizes for each plane > VLC vlc[4]; // VLC for each plane > + VLC_MULTI multi[4]; // Buffer for joint VLC data > int (*magy_decode_slice)(AVCodecContext *avctx, void *tdata, > int j, int threadnr); > LLVidDSPContext llviddsp; > } MagicYUVContext; > > static int huff_build(const uint8_t len[], uint16_t codes_pos[33], > - VLC *vlc, int nb_elems, void *logctx) > + VLC *vlc, VLC_MULTI *multi, int nb_elems, void *logctx) > { > HuffEntry he[4096]; > > @@ -84,7 +87,8 @@ static int huff_build(const uint8_t len[], uint16_t codes_pos[33], > he[--codes_pos[len[i]]] = (HuffEntry){ len[i], i }; > > ff_free_vlc(vlc); > - return ff_init_vlc_from_lengths(vlc, FFMIN(he[0].len, 12), nb_elems, > + ff_free_vlc_multi(multi); > + return ff_init_vlc_multi_from_lengths(vlc, multi, FFMIN(he[0].len, VLC_BITS), nb_elems, nb_elems, > &he[0].len, sizeof(he[0]), > &he[0].sym, sizeof(he[0]), sizeof(he[0].sym), > 0, 0, logctx); > @@ -111,6 +115,22 @@ static void magicyuv_median_pred16(uint16_t *dst, const uint16_t *src1, > *left_top = lt; > } > > +#define READ_PLANE(dst, plane, b, c) \ > +{ \ > + x = 0; \ > + for (; CACHED_BITSTREAM_READER && x < width-c && get_bits_left(&gb) > 0;) {\ > + ret = get_vlc_multi(&gb, (uint8_t *)dst + x * b, multi, \ > + vlc, vlc_bits, 3); \ > + if (ret > 0) \ > + x += ret; \ > + if (ret <= 0) \ > + return AVERROR_INVALIDDATA; \ > + } \ > + for (; x < width && get_bits_left(&gb) > 0; x++) \ > + dst[x] = get_vlc2(&gb, vlc, vlc_bits, 3); \ > + dst += stride; \ > +} > + > static int magy_decode_slice10(AVCodecContext *avctx, void *tdata, > int j, int threadnr) > { > @@ -130,6 +150,9 @@ static int magy_decode_slice10(AVCodecContext *avctx, void *tdata, > int sheight = AV_CEIL_RSHIFT(s->slice_height, s->vshift[i]); > ptrdiff_t fake_stride = (p->linesize[i] / 2) * (1 + interlaced); > ptrdiff_t stride = p->linesize[i] / 2; > + const VLC_MULTI_ELEM *const multi = s->multi[i].table; > + const VLCElem *const vlc = s->vlc[i].table; > + const int vlc_bits = s->vlc[i].bits; > int flags, pred; > int ret = init_get_bits8(&gb, s->buf + s->slices[i][j].start, > s->slices[i][j].size); > @@ -151,20 +174,8 @@ static int magy_decode_slice10(AVCodecContext *avctx, void *tdata, > dst += stride; > } > } else { > - for (k = 0; k < height; k++) { > - for (x = 0; x < width; x++) { > - int pix; > - if (get_bits_left(&gb) <= 0) > - return AVERROR_INVALIDDATA; > - > - pix = get_vlc2(&gb, s->vlc[i].table, s->vlc[i].bits, 3); > - if (pix < 0) > - return AVERROR_INVALIDDATA; > - > - dst[x] = pix; > - } > - dst += stride; > - } > + for (k = 0; k < height; k++) > + READ_PLANE(dst, i, 2, 3) > } > > switch (pred) { > @@ -261,6 +272,9 @@ static int magy_decode_slice(AVCodecContext *avctx, void *tdata, > ptrdiff_t fake_stride = p->linesize[i] * (1 + interlaced); > ptrdiff_t stride = p->linesize[i]; > const uint8_t *slice = s->buf + s->slices[i][j].start; > + const VLC_MULTI_ELEM *const multi = s->multi[i].table; > + const VLCElem *const vlc = s->vlc[i].table; > + const int vlc_bits = s->vlc[i].bits; > int flags, pred; > > flags = bytestream_get_byte(&slice); > @@ -280,20 +294,8 @@ static int magy_decode_slice(AVCodecContext *avctx, void *tdata, > if (ret < 0) > return ret; > > - for (k = 0; k < height; k++) { > - for (x = 0; x < width; x++) { > - int pix; > - if (get_bits_left(&gb) <= 0) > - return AVERROR_INVALIDDATA; > - > - pix = get_vlc2(&gb, s->vlc[i].table, s->vlc[i].bits, 3); > - if (pix < 0) > - return AVERROR_INVALIDDATA; > - > - dst[x] = pix; > - } > - dst += stride; > - } > + for (k = 0; k < height; k++) > + READ_PLANE(dst, i, 1, 5) > } > > switch (pred) { Who reviewed this ? This is a straight out of array write writing 8 bytes while the check assumes its max 5 ==16861==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x631000024800 at pc 0x000001552992 bp 0x7ffd8d34bf10 sp 0x7ffd8d34bf08 WRITE of size 8 at 0x631000024800 thread T0 #0 0x1552991 in bits_read_vlc_multi_be ffmpeg/libavcodec/bitstream_template.h:531:9 #1 0x15453d0 in magy_decode_slice ffmpeg/libavcodec/magicyuv.c:302:17 #2 0x13f3738 in avcodec_default_execute2 ffmpeg/libavcodec/avcodec.c:76:17 #3 0x153fba5 in magy_decode_frame ffmpeg/libavcodec/magicyuv.c:663:5 #4 0x142d60e in decode_simple_internal ffmpeg/libavcodec/decode.c:430:20 #5 0x142d60e in decode_simple_receive_frame ffmpeg/libavcodec/decode.c:609 #6 0x142d60e in decode_receive_frame_internal ffmpeg/libavcodec/decode.c:637 #7 0x142c42f in avcodec_send_packet ffmpeg/libavcodec/decode.c:734:15 #8 0x4ce9df in LLVMFuzzerTestOneInput ffmpeg/tools/target_dec_fuzzer.c:579:25 #9 0x29f5f0d in fuzzer::Fuzzer::ExecuteCallback(unsigned char const*, unsigned long) Fuzzer/build/../FuzzerLoop.cpp:495:13 #10 0x29eaae2 in fuzzer::RunOneTest(fuzzer::Fuzzer*, char const*, unsigned long) Fuzzer/build/../FuzzerDriver.cpp:273:6 #11 0x29efce1 in fuzzer::FuzzerDriver(int*, char***, int (*)(unsigned char const*, unsigned long)) Fuzzer/build/../FuzzerDriver.cpp:690:9 #12 0x29ea7c0 in main Fuzzer/build/../FuzzerMain.cpp:20:10 #13 0x7f15a835ec86 in __libc_start_main /build/glibc-CVJwZb/glibc-2.27/csu/../csu/libc-start.c:310 #14 0x420339 in _start (ffmpeg/tools/target_dec_magicyuv_fuzzer+0x420339) the multi vlc code is not documented, teh function writing out of array is one of the very few functions in bitstream_template.h that is undocumented why do we in 2023 add undocumented non trivial functions into files where basically every function prior is documented ? [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB I know you won't believe me, but the highest form of Human Excellence is to question oneself and others. -- Socrates