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specrec: better handle unexpected PS (CVE-2018-20360/CVE-2018-20199) #38

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Aug 26, 2019
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specrec: better handle unexpected PS (CVE-2018-20360/CVE-2018-20199) #38

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3b80a57
specrec: better handle unexpected PS
hlef Aug 19, 2019
6823e66
ps_dec: sanitize iid_index before mixing
hlef Aug 23, 2019
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14 changes: 14 additions & 0 deletions libfaad/ps_dec.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1508,6 +1508,20 @@ static void ps_mix_phase(ps_info *ps, qmf_t X_left[38][64], qmf_t X_right[38][64

//printf("%d\n", ps->iid_index[env][bk]);

/* index range is supposed to be -7...7 or -15...15 depending on iid_mode
(Table 8.24, ISO/IEC 14496-3:2005).
if it is outside these boundaries, this is most likely an error. sanitize
it and try to process further. */
if (ps->iid_index[env][bk] < -no_iid_steps) {
fprintf(stderr, "Warning: invalid iid_index: %d < %d\n", ps->iid_index[env][bk],
-no_iid_steps);
ps->iid_index[env][bk] = -no_iid_steps;
} else if (ps->iid_index[env][bk] > no_iid_steps) {
fprintf(stderr, "Warning: invalid iid_index: %d > %d\n", ps->iid_index[env][bk],
no_iid_steps);
ps->iid_index[env][bk] = no_iid_steps;
}

/* calculate the scalefactors c_1 and c_2 from the intensity differences */
c_1 = sf_iid[no_iid_steps + ps->iid_index[env][bk]];
c_2 = sf_iid[no_iid_steps - ps->iid_index[env][bk]];
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18 changes: 9 additions & 9 deletions libfaad/specrec.c
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Original file line number Diff line number Diff line change
Expand Up @@ -915,18 +915,18 @@ uint8_t reconstruct_single_channel(NeAACDecStruct *hDecoder, ic_stream *ics,
/* element_output_channels not set yet */
hDecoder->element_output_channels[hDecoder->fr_ch_ele] = output_channels;
} else if (hDecoder->element_output_channels[hDecoder->fr_ch_ele] != output_channels) {
/* element inconsistency */

/* this only happens if PS is actually found but not in the first frame
/* element inconsistency
* this only happens if PS is actually found but not in the first frame
* this means that there is only 1 bitstream element!
*/

/* reset the allocation */
hDecoder->element_alloced[hDecoder->fr_ch_ele] = 0;

hDecoder->element_output_channels[hDecoder->fr_ch_ele] = output_channels;

//return 21;
if (hDecoder->fr_channels == 1) {
/* reset the allocation */
hDecoder->element_alloced[hDecoder->fr_ch_ele] = 0;
hDecoder->element_output_channels[hDecoder->fr_ch_ele] = output_channels;
} else {
return 21;
}
}

if (hDecoder->element_alloced[hDecoder->fr_ch_ele] == 0)
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