| Message ID | 20200731112241.8948-5-andreas.rheinhardt@gmail.com |
|---|---|
| State | Accepted |
| Commit | bd076cacc313b19e5af895df6d332aa48c33cf2a |
| Headers | show |
| Series | [FFmpeg-devel,1/8] avcodec/smacker: Remove write-only and unused variables | expand |
| Context | Check | Description |
|---|---|---|
| andriy/default | pending | |
| andriy/make | success | Make finished |
| andriy/make_fate | success | Make fate finished |
On 7/31/20, Andreas Rheinhardt <andreas.rheinhardt@gmail.com> wrote: > The extradata for Smacker video contains Huffman trees as well as a > field containing the size (in bytes) of said Huffman tree when stored > as a table. Due to three special values the decoder allocates more than > the size field indicates; yet when it parses the table it only errors > out if the number of elements exceeds the number of allocated elements > and not the number of elements as indicated by the size field. As a > consequence, there might be less than three elements available at the > end, so that another check for this is necessary. > > This commit changes this: It is always made sure that the three elements > reserved to (potentially) use them to store the special values are not > used to store ordinary tree entries. This allows to remove the extra > check at the end. > > Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com> > --- > libavcodec/smacker.c | 12 +++--------- > 1 file changed, 3 insertions(+), 9 deletions(-) > Probably OK
diff --git a/libavcodec/smacker.c b/libavcodec/smacker.c index b6245a0ce1..8a4d88cfed 100644 --- a/libavcodec/smacker.c +++ b/libavcodec/smacker.c @@ -137,7 +137,7 @@ static int smacker_decode_bigtree(GetBitContext *gb, HuffContext *hc, return AVERROR_INVALIDDATA; } - if (hc->current + 1 >= hc->length) { + if (hc->current >= hc->length) { av_log(NULL, AV_LOG_ERROR, "Tree size exceeded!\n"); return AVERROR_INVALIDDATA; } @@ -244,9 +244,9 @@ static int smacker_decode_header_tree(SmackVContext *smk, GetBitContext *gb, int ctx.recode2 = h[1].values; ctx.last = last; - huff.length = ((size + 3) >> 2) + 4; + huff.length = (size + 3) >> 2; huff.current = 0; - huff.values = av_mallocz_array(huff.length, sizeof(int)); + huff.values = av_mallocz_array(huff.length + 3, sizeof(huff.values[0])); if (!huff.values) { err = AVERROR(ENOMEM); goto error; @@ -259,12 +259,6 @@ static int smacker_decode_header_tree(SmackVContext *smk, GetBitContext *gb, int if(ctx.last[0] == -1) ctx.last[0] = huff.current++; if(ctx.last[1] == -1) ctx.last[1] = huff.current++; if(ctx.last[2] == -1) ctx.last[2] = huff.current++; - if (ctx.last[0] >= huff.length || - ctx.last[1] >= huff.length || - ctx.last[2] >= huff.length) { - av_log(smk->avctx, AV_LOG_ERROR, "Huffman codes out of range\n"); - err = AVERROR_INVALIDDATA; - } *recodes = huff.values;
The extradata for Smacker video contains Huffman trees as well as a field containing the size (in bytes) of said Huffman tree when stored as a table. Due to three special values the decoder allocates more than the size field indicates; yet when it parses the table it only errors out if the number of elements exceeds the number of allocated elements and not the number of elements as indicated by the size field. As a consequence, there might be less than three elements available at the end, so that another check for this is necessary. This commit changes this: It is always made sure that the three elements reserved to (potentially) use them to store the special values are not used to store ordinary tree entries. This allows to remove the extra check at the end. Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com> --- libavcodec/smacker.c | 12 +++--------- 1 file changed, 3 insertions(+), 9 deletions(-)