Commit message: Fixes #264.

The JP2 decoder was allowing the decoding of a code stream to be
attempted when the stream has inconsistent values for the number of
components and/or the component types.  For such invalid streams,
only a warning would be issued and decoding would proceed.  This is
dangerous, however, as it can lead to many unexpected paths through
the code, which in some cases have been demonstrated to result in
security vulnerabilities.  This code change makes decoding of these
types invalid code streams a hard error.
CVE: CVE-2021-26927
CWE: CWE-125
Vulnerability description: A flaw was found in jasper before 2.0.25. A null pointer dereference in jp2_decode in jp2_dec.c may lead to program crash and denial of service.

Project: jasper
File: jp2_dec.c

jas_image_t *jp2_decode(jas_stream_t *in, const char *optstr)
{
	jp2_box_t *box;
	int found;
	jas_image_t *image;
	jp2_dec_t *dec;
	bool samedtype;
	int dtype;
	unsigned int i;
	jp2_cmap_t *cmapd;
	jp2_pclr_t *pclrd;
	jp2_cdef_t *cdefd;
	unsigned int channo;
	int newcmptno;
	int_fast32_t *lutents;
#if 0
	jp2_cdefchan_t *cdefent;
	int cmptno;
#endif
	jp2_cmapent_t *cmapent;
	jas_icchdr_t icchdr;
	jas_iccprof_t *iccprof;

	dec = 0;
	box = 0;
	image = 0;

	JAS_DBGLOG(100, ("jp2_decode(%p, \"%s\")\n", in, optstr));

	if (!(dec = jp2_dec_create())) {
		goto error;
	}

	/* Get the first box.  This should be a JP box. */
	if (!(box = jp2_box_get(in))) {
		jas_eprintf("error: cannot get box\n");
		goto error;
	}
	if (box->type != JP2_BOX_JP) {
		jas_eprintf("error: expecting signature box\n");
		goto error;
	}
	if (box->data.jp.magic != JP2_JP_MAGIC) {
		jas_eprintf("incorrect magic number\n");
		goto error;
	}
	jp2_box_destroy(box);
	box = 0;

	/* Get the second box.  This should be a FTYP box. */
	if (!(box = jp2_box_get(in))) {
		goto error;
	}
	if (box->type != JP2_BOX_FTYP) {
		jas_eprintf("expecting file type box\n");
		goto error;
	}
	jp2_box_destroy(box);
	box = 0;

	/* Get more boxes... */
	found = 0;
	while ((box = jp2_box_get(in))) {
		if (jas_getdbglevel() >= 1) {
			jas_eprintf("got box type %s\n", box->info->name);
		}
		switch (box->type) {
		case JP2_BOX_JP2C:
			found = 1;
			break;
		case JP2_BOX_IHDR:
			if (!dec->ihdr) {
				dec->ihdr = box;
				box = 0;
			}
			break;
		case JP2_BOX_BPCC:
			if (!dec->bpcc) {
				dec->bpcc = box;
				box = 0;
			}
			break;
		case JP2_BOX_CDEF:
			if (!dec->cdef) {
				dec->cdef = box;
				box = 0;
			}
			break;
		case JP2_BOX_PCLR:
			if (!dec->pclr) {
				dec->pclr = box;
				box = 0;
			}
			break;
		case JP2_BOX_CMAP:
			if (!dec->cmap) {
				dec->cmap = box;
				box = 0;
			}
			break;
		case JP2_BOX_COLR:
			if (!dec->colr) {
				dec->colr = box;
				box = 0;
			}
			break;
		}
		if (box) {
			jp2_box_destroy(box);
			box = 0;
		}
		if (found) {
			break;
		}
	}

	if (!found) {
		jas_eprintf("error: no code stream found\n");
		goto error;
	}

	if (!(dec->image = jpc_decode(in, optstr))) {
		jas_eprintf("error: cannot decode code stream\n");
		goto error;
	}

	/* An IHDR box must be present. */
	if (!dec->ihdr) {
		jas_eprintf("error: missing IHDR box\n");
		goto error;
	}

	/* Does the number of components indicated in the IHDR box match
	  the value specified in the code stream? */
	if (dec->ihdr->data.ihdr.numcmpts != JAS_CAST(jas_uint,
	  jas_image_numcmpts(dec->image))) {
		jas_eprintf("warning: number of components mismatch\n");
	}

	/* At least one component must be present. */
	if (!jas_image_numcmpts(dec->image)) {
		jas_eprintf("error: no components\n");
		goto error;
	}

	/* Determine if all components have the same data type. */
	samedtype = true;
	dtype = jas_image_cmptdtype(dec->image, 0);
	for (i = 1; i < JAS_CAST(jas_uint, jas_image_numcmpts(dec->image)); ++i) {
		if (jas_image_cmptdtype(dec->image, i) != dtype) {
			samedtype = false;
			break;
		}
	}

	/* Is the component data type indicated in the IHDR box consistent
	  with the data in the code stream? */
	if ((samedtype && dec->ihdr->data.ihdr.bpc != JP2_DTYPETOBPC(dtype)) ||
	  (!samedtype && dec->ihdr->data.ihdr.bpc != JP2_IHDR_BPCNULL)) {
		jas_eprintf("warning: component data type mismatch (IHDR)\n");
	}

	/* Is the compression type supported? */
	if (dec->ihdr->data.ihdr.comptype != JP2_IHDR_COMPTYPE) {
		jas_eprintf("error: unsupported compression type\n");
		goto error;
	}

	if (dec->bpcc) {
		/* Is the number of components indicated in the BPCC box
		  consistent with the code stream data? */
		if (dec->bpcc->data.bpcc.numcmpts != JAS_CAST(jas_uint, jas_image_numcmpts(
		  dec->image))) {
			jas_eprintf("warning: number of components mismatch\n");
		}
		/* Is the component data type information indicated in the BPCC
		  box consistent with the code stream data? */
		if (!samedtype) {
			for (i = 0; i < JAS_CAST(jas_uint, jas_image_numcmpts(dec->image));
			  ++i) {
				if (jas_image_cmptdtype(dec->image, i) !=
				  JP2_BPCTODTYPE(dec->bpcc->data.bpcc.bpcs[i])) {
					jas_eprintf("warning: component data type mismatch (BPCC)\n");
				}
			}
		} else {
			jas_eprintf("warning: superfluous BPCC box\n");
		}
	}

	/* A COLR box must be present. */
	if (!dec->colr) {
		jas_eprintf("error: no COLR box\n");
		goto error;
	}

	switch (dec->colr->data.colr.method) {
	case JP2_COLR_ENUM:
		jas_image_setclrspc(dec->image, jp2_getcs(&dec->colr->data.colr));
		break;
	case JP2_COLR_ICC:
		iccprof = jas_iccprof_createfrombuf(dec->colr->data.colr.iccp,
		  dec->colr->data.colr.iccplen);
		if (!iccprof) {
			jas_eprintf("error: failed to parse ICC profile\n");
			goto error;
		}
		jas_iccprof_gethdr(iccprof, &icchdr);
		jas_eprintf("ICC Profile CS %08x\n", icchdr.colorspc);
		jas_image_setclrspc(dec->image, fromiccpcs(icchdr.colorspc));
		dec->image->cmprof_ = jas_cmprof_createfromiccprof(iccprof);
		if (!dec->image->cmprof_) {
			jas_iccprof_destroy(iccprof);
			goto error;
		}
		jas_iccprof_destroy(iccprof);
		break;
	}

	/* If a CMAP box is present, a PCLR box must also be present. */
	if (dec->cmap && !dec->pclr) {
		jas_eprintf("warning: missing PCLR box or superfluous CMAP box\n");
		jp2_box_destroy(dec->cmap);
		dec->cmap = 0;
	}

	/* If a CMAP box is not present, a PCLR box must not be present. */
	if (!dec->cmap && dec->pclr) {
		jas_eprintf("warning: missing CMAP box or superfluous PCLR box\n");
		jp2_box_destroy(dec->pclr);
		dec->pclr = 0;
	}

	/* Determine the number of channels (which is essentially the number
	  of components after any palette mappings have been applied). */
	dec->numchans = dec->cmap ? dec->cmap->data.cmap.numchans :
	  JAS_CAST(jas_uint, jas_image_numcmpts(dec->image));

	/* Perform a basic sanity check on the CMAP box if present. */
	if (dec->cmap) {
		for (i = 0; i < dec->numchans; ++i) {
			/* Is the component number reasonable? */
			if (dec->cmap->data.cmap.ents[i].cmptno >= JAS_CAST(jas_uint,
			  jas_image_numcmpts(dec->image))) {
				jas_eprintf("error: invalid component number in CMAP box\n");
				goto error;
			}
			/* Is the LUT index reasonable? */
			if (dec->cmap->data.cmap.ents[i].pcol >=
			  dec->pclr->data.pclr.numchans) {
				jas_eprintf("error: invalid CMAP LUT index\n");
				goto error;
			}
		}
	}

	/* Allocate space for the channel-number to component-number LUT. */
	if (!(dec->chantocmptlut = jas_alloc2(dec->numchans,
	  sizeof(uint_fast16_t)))) {
		jas_eprintf("error: no memory\n");
		goto error;
	}

	if (!dec->cmap) {
		for (i = 0; i < dec->numchans; ++i) {
			dec->chantocmptlut[i] = i;
		}
	} else {
		cmapd = &dec->cmap->data.cmap;
		pclrd = &dec->pclr->data.pclr;
		cdefd = &dec->cdef->data.cdef;
		for (channo = 0; channo < cmapd->numchans; ++channo) {
			cmapent = &cmapd->ents[channo];
			if (cmapent->map == JP2_CMAP_DIRECT) {
				dec->chantocmptlut[channo] = channo;
			} else if (cmapent->map == JP2_CMAP_PALETTE) {
				if (!pclrd->numlutents) {
					goto error;
				}
				lutents = jas_alloc2(pclrd->numlutents, sizeof(int_fast32_t));
				if (!lutents) {
					goto error;
				}
				for (i = 0; i < pclrd->numlutents; ++i) {
					lutents[i] = pclrd->lutdata[cmapent->pcol + i * pclrd->numchans];
				}
				newcmptno = jas_image_numcmpts(dec->image);
				jas_image_depalettize(dec->image, cmapent->cmptno,
				  pclrd->numlutents, lutents,
				  JP2_BPCTODTYPE(pclrd->bpc[cmapent->pcol]), newcmptno);
				dec->chantocmptlut[channo] = newcmptno;
				jas_free(lutents);
#if 0
				if (dec->cdef) {
					cdefent = jp2_cdef_lookup(cdefd, channo);
					if (!cdefent) {
						abort();
					}
				jas_image_setcmpttype(dec->image, newcmptno, jp2_getct(jas_image_clrspc(dec->image), cdefent->type, cdefent->assoc));
				} else {
				jas_image_setcmpttype(dec->image, newcmptno, jp2_getct(jas_image_clrspc(dec->image), 0, channo + 1));
				}
#else
				/* suppress -Wunused-but-set-variable */
				(void)cdefd;
#endif
			} else {
				jas_eprintf("error: invalid MTYP in CMAP box\n");
				goto error;
			}
		}
	}

	/* Ensure that the number of channels being used by the decoder
	  matches the number of image components. */
	if (dec->numchans != jas_image_numcmpts(dec->image)) {
		jas_eprintf("error: mismatch in number of components (%d != %d)\n",
		  dec->numchans, jas_image_numcmpts(dec->image));
		goto error;
	}

	/* Mark all components as being of unknown type. */

	for (i = 0; i < JAS_CAST(jas_uint, jas_image_numcmpts(dec->image)); ++i) {
		jas_image_setcmpttype(dec->image, i, JAS_IMAGE_CT_UNKNOWN);
	}

	/* Determine the type of each component. */
	if (dec->cdef) {
		for (i = 0; i < dec->cdef->data.cdef.numchans; ++i) {
			/* Is the channel number reasonable? */
			if (dec->cdef->data.cdef.ents[i].channo >= dec->numchans) {
				jas_eprintf("error: invalid channel number in CDEF box\n");
				goto error;
			}
			jas_image_setcmpttype(dec->image,
			  dec->chantocmptlut[dec->cdef->data.cdef.ents[i].channo],
			  jp2_getct(jas_image_clrspc(dec->image),
			  dec->cdef->data.cdef.ents[i].type,
			  dec->cdef->data.cdef.ents[i].assoc));
		}
	} else {
		for (i = 0; i < dec->numchans; ++i) {
			jas_image_setcmpttype(dec->image, dec->chantocmptlut[i],
			  jp2_getct(jas_image_clrspc(dec->image), 0, i + 1));
		}
	}

	/* Delete any components that are not of interest. */
	for (i = jas_image_numcmpts(dec->image); i > 0; --i) {
		if (jas_image_cmpttype(dec->image, i - 1) == JAS_IMAGE_CT_UNKNOWN) {
			jas_image_delcmpt(dec->image, i - 1);
		}
	}

	/* Ensure that some components survived. */
	if (!jas_image_numcmpts(dec->image)) {
		jas_eprintf("error: no components\n");
		goto error;
	}
#if 0
jas_eprintf("no of components is %d\n", jas_image_numcmpts(dec->image));
#endif

	/* Prevent the image from being destroyed later. */
	image = dec->image;
	dec->image = 0;

	jp2_dec_destroy(dec);

	return image;

error:
	if (box) {
		jp2_box_destroy(box);
	}
	if (dec) {
		jp2_dec_destroy(dec);
	}
	return 0;
}