[FFmpeg-devel] [PATCH v2 2/4] libavcodec/jpeg2000 Fix PCRL Progression Order check

[gautamramk at gmail.com]

From: Gautam Ramakrishnan <gautamramk at gmail.com>

The PCRL progression checks were incomplete. This patch
modifes completes the check. Tested on p1_05.j2k.
---
 libavcodec/jpeg2000dec.c | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/libavcodec/jpeg2000dec.c b/libavcodec/jpeg2000dec.c
index 48ca1c37a5..adaac192e9 100644
--- a/libavcodec/jpeg2000dec.c
+++ b/libavcodec/jpeg2000dec.c
@@ -1465,23 +1465,30 @@ static int jpeg2000_decode_packets_po_iteration(Jpeg2000DecoderContext *s, Jpeg2
                     Jpeg2000Component *comp     = tile->comp + compno;
                     Jpeg2000CodingStyle *codsty = tile->codsty + compno;
                     Jpeg2000QuantStyle *qntsty  = tile->qntsty + compno;
-                    int xc = x / s->cdx[compno];
-                    int yc = y / s->cdy[compno];
+
+                    if (!s->cdx[compno] || !s->cdy[compno])
+                        return AVERROR_INVALIDDATA;
 
                     for (reslevelno = RSpoc; reslevelno < FFMIN(codsty->nreslevels, REpoc); reslevelno++) {
                         unsigned prcx, prcy;
                         uint8_t reducedresno = codsty->nreslevels - 1 -reslevelno; //  ==> N_L - r
                         Jpeg2000ResLevel *rlevel = comp->reslevel + reslevelno;
+                        int trx0, try0;
 
-                        if (yc % (1LL << (rlevel->log2_prec_height + reducedresno)) && y != tile->coord[1][0]) //FIXME this is a subset of the check
-                            continue;
+                        trx0 = ff_jpeg2000_ceildiv(tile->coord[0][0], s->cdx[compno] << reducedresno);
+                        try0 = ff_jpeg2000_ceildiv(tile->coord[1][0], s->cdy[compno] << reducedresno);
 
-                        if (xc % (1LL << (rlevel->log2_prec_width + reducedresno)) && x != tile->coord[0][0]) //FIXME this is a subset of the check
-                            continue;
+                        if (!(y % ((uint64_t)s->cdy[compno] << (rlevel->log2_prec_height + reducedresno)) == 0 ||
+                             (y == tile->coord[1][0] && (try0 << reducedresno) % (1U << (reducedresno + rlevel->log2_prec_height)))))
+                             continue;
+
+                        if (!(x % ((uint64_t)s->cdx[compno] << (rlevel->log2_prec_width + reducedresno)) == 0 ||
+                             (x == tile->coord[0][0] && (trx0 << reducedresno) % (1U << (reducedresno + rlevel->log2_prec_width)))))
+                             continue;
 
                         // check if a precinct exists
-                        prcx   = ff_jpeg2000_ceildivpow2(xc, reducedresno) >> rlevel->log2_prec_width;
-                        prcy   = ff_jpeg2000_ceildivpow2(yc, reducedresno) >> rlevel->log2_prec_height;
+                        prcx   = ff_jpeg2000_ceildiv(x, s->cdx[compno] << reducedresno) >> rlevel->log2_prec_width;
+                        prcy   = ff_jpeg2000_ceildiv(y, s->cdy[compno] << reducedresno) >> rlevel->log2_prec_height;
                         prcx  -= ff_jpeg2000_ceildivpow2(comp->coord_o[0][0], reducedresno) >> rlevel->log2_prec_width;
                         prcy  -= ff_jpeg2000_ceildivpow2(comp->coord_o[1][0], reducedresno) >> rlevel->log2_prec_height;
 
-- 
2.17.1