[FFmpeg-devel] [PATCH] sbr_qmf_analysis: sanitize input for 32-bit imdct
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 --- 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 ___ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
Re: [FFmpeg-devel] [PATCH] sbr_qmf_analysis: sanitize input for 32-bit imdct
On 19.11.2015 01:02, Andreas Cadhalpun wrote: > 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 > --- > > 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; > Ping. If nobody objects, I'll push this soon, as it fixes crashes. Best regards, Andreas ___ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
Re: [FFmpeg-devel] [PATCH] sbr_qmf_analysis: sanitize input for 32-bit imdct
On 02.12.2015 20:58, Andreas Cadhalpun wrote: > On 19.11.2015 01:02, Andreas Cadhalpun wrote: >> 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 >> --- >> >> 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; >> > > Ping. > > If nobody objects, I'll push this soon, as it fixes crashes. I pushed this now. Best regards, Andreas ___ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel