If the input contains too many too large values, the imdct can overflow.
Even if it didn't, the output would be larger than the valid range of 29
bits.
Note that this is a very delicate limit: Allowing values up to 1<<25
does not prevent input larger than 1<<29 from arriving at
sbr_sum_square, while limiting values to 1<<23 breaks the
fate-aac-fixed-al_sbr_hq_cm_48_5.1 test.
Signed-off-by: Andreas Cadhalpun <andreas.cadhal...@googlemail.com>
---
Nedeljko, do you have an explanation why larger input values here
are invalid?
By the way, the imdct calculations in imdct_and_windowing and
sbr_qmf_synthesis can also overflow, so maybe need a similar check.
---
libavcodec/aacsbr_template.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/libavcodec/aacsbr_template.c b/libavcodec/aacsbr_template.c
index 66f4159..f48ddd0 100644
--- a/libavcodec/aacsbr_template.c
+++ b/libavcodec/aacsbr_template.c
@@ -1153,6 +1153,9 @@ static void sbr_qmf_analysis(AVFloatDSPContext *dsp,
FFTContext *mdct,
INTFLOAT z[320], INTFLOAT W[2][32][32][2], int
buf_idx)
{
int i;
+#if USE_FIXED
+ int j;
+#endif
memcpy(x , x+1024, (320-32)*sizeof(x[0]));
memcpy(x+288, in, 1024*sizeof(x[0]));
for (i = 0; i < 32; i++) { // numTimeSlots*RATE = 16*2 as 960 sample frames
@@ -1160,6 +1163,21 @@ static void sbr_qmf_analysis(AVFloatDSPContext *dsp,
FFTContext *mdct,
dsp->vector_fmul_reverse(z, sbr_qmf_window_ds, x, 320);
sbrdsp->sum64x5(z);
sbrdsp->qmf_pre_shuffle(z);
+#if USE_FIXED
+ for (j = 64; j < 128; j++) {
+ if (z[j] > 1<<24) {
+ av_log(NULL, AV_LOG_WARNING,
+ "sbr_qmf_analysis: value %09d too large, setting to
%09d\n",
+ z[j], 1<<24);
+ z[j] = 1<<24;
+ } else if (z[j] < -(1<<24)) {
+ av_log(NULL, AV_LOG_WARNING,
+ "sbr_qmf_analysis: value %09d too small, setting to
%09d\n",
+ z[j], -(1<<24));
+ z[j] = -(1<<24);
+ }
+ }
+#endif
mdct->imdct_half(mdct, z, z+64);
sbrdsp->qmf_post_shuffle(W[buf_idx][i], z);
x += 32;
--
2.6.2
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