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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 ) */ } /* if ( pJointStereoData->complex_coef == 1 ) */
/* 4. upmix process */ /* 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 */ /* 0.1 in Q-3.34 */
const FIXP_DBL pointOne = 0x66666666; /* 0.8 */ const FIXP_DBL pointOne = 0x66666666; /* 0.8 */
/* Shift value for the downmix */ /* Shift value for the downmix */
@ -1039,34 +1039,24 @@ void CJointStereo_ApplyMS(
the downmix. "dmx_re" and "specL" are two different pointers the downmix. "dmx_re" and "specL" are two different pointers
pointing to separate arrays, which may or may not contain the pointing to separate arrays, which may or may not contain the
same data (with different scaling). 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] */ side = fMultAddDiv2(fMultDiv2(alpha_re_tmp, *p2dmxRe++),
FIXP_DBL help1 = 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] */ left = ((*p2CoeffL) >> 2) + side;
FIXP_DBL tmp = (*p2dmxIm++) << shift_dmx; right = ((*p2CoeffL) >> 2) - side;
right = (FIXP_DBL)((LONG)right * pred_dir);
/* help2: alpha_im[i] * dmx_im[i] */ *p2CoeffL++ = SATURATE_LEFT_SHIFT_ALT(left, 2, DFRACT_BITS);
FIXP_DBL help2 = fMultDiv2(alpha_im_tmp, tmp); *p2CoeffR++ = SATURATE_LEFT_SHIFT_ALT(right, 2, DFRACT_BITS);
/* 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++;
} }
} }