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Overcome potential integer overflows in M/S module for complex prediction. 

Bug: 131430997
Test: atest DecoderTestXheAac ; atest DecoderTestAacDrc
Change-Id: Ic0648203b6a61ebff8bcc93c4b1099e033bc6860
This commit is contained in:
Fraunhofer IIS FDK 2019-09-20 14:00:27 +02:00 committed by Jean-Michel Trivi
parent 40d2a1d8b0
commit 1b4a3bedbb
1 changed files with 15 additions and 25 deletions
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40
libAACdec/src/stereo.cpp
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@ -989,7 +989,7 @@ void CJointStereo_ApplyMS(
} /* if ( pJointStereoData->complex_coef == 1 ) */
/* 4. upmix process */
INT pred_dir = cplxPredictionData->pred_dir ? -1 : 1;
LONG pred_dir = cplxPredictionData->pred_dir ? -1 : 1;
/* 0.1 in Q-3.34 */
const FIXP_DBL pointOne = 0x66666666; /* 0.8 */
/* Shift value for the downmix */
@ -1039,34 +1039,24 @@ void CJointStereo_ApplyMS(
the downmix. "dmx_re" and "specL" are two different pointers
pointing to separate arrays, which may or may not contain the
same data (with different scaling).
specL[i] = + (specL[i] + side);
specR[i] = -/+ (specL[i] - side);
*/
FIXP_DBL side, left, right;
/* help1: alpha_re[i] * dmx_re[i] */
FIXP_DBL help1 = fMultDiv2(alpha_re_tmp, *p2dmxRe++);
side = fMultAddDiv2(fMultDiv2(alpha_re_tmp, *p2dmxRe++),
alpha_im_tmp, (*p2dmxIm++) << shift_dmx);
side = ((*p2CoeffR) >> 2) -
(FIXP_DBL)SATURATE_SHIFT(side, -(help3_shift - 2),
DFRACT_BITS - 2);
/* tmp: dmx_im[i] */
FIXP_DBL tmp = (*p2dmxIm++) << shift_dmx;
left = ((*p2CoeffL) >> 2) + side;
right = ((*p2CoeffL) >> 2) - side;
right = (FIXP_DBL)((LONG)right * pred_dir);
/* help2: alpha_im[i] * dmx_im[i] */
FIXP_DBL help2 = fMultDiv2(alpha_im_tmp, tmp);
/* help3: alpha_re[i] * dmx_re[i] + alpha_im[i] * dmx_im[i] */
FIXP_DBL help3 = help1 + help2;
/* side (= help4) = specR[i] - (dmx_re[i] * specL[i] + alpha_im[i]
* * dmx_im[i]) */
FIXP_DBL help4 = *p2CoeffR - scaleValue(help3, help3_shift);
/* We calculate the left and right output by using the helper
* function */
/* specR[i] = -/+ (specL[i] - side); */
*p2CoeffR =
(FIXP_DBL)((LONG)(*p2CoeffL - help4) * (LONG)pred_dir);
p2CoeffR++;
/* specL[i] = specL[i] + side; */
*p2CoeffL = *p2CoeffL + help4;
p2CoeffL++;
*p2CoeffL++ = SATURATE_LEFT_SHIFT_ALT(left, 2, DFRACT_BITS);
*p2CoeffR++ = SATURATE_LEFT_SHIFT_ALT(right, 2, DFRACT_BITS);
}
}