Fix for the Divide-by-zero in impd_drc_td_drc_gain_calc_init

These changes handle the divide-by-zero runtime error
reported when the successive drc gain coordinates
have same x coordinates.

Bug: ossFuzz:62237
Test: poc in bug

5 files changed, 76 insertions, 83 deletions

diff --git a/encoder/drc_src/impd_drc_enc.c b/encoder/drc_src/impd_drc_enc.c
index 1b92856..7e835f7 100644
--- a/encoder/drc_src/impd_drc_enc.c
+++ b/encoder/drc_src/impd_drc_enc.c
@@ -205,7 +205,7 @@ IA_ERRORCODE impd_drc_gain_enc_init(ia_drc_gain_enc_struct *pstr_gain_enc,
         pstr_gain_enc->str_drc_compand[0][j].initial_volume = 0.0f;
 
         err_code = impd_drc_td_drc_gain_calc_init(pstr_gain_enc, 0, j);
-        if (err_code & IA_FATAL_ERROR) {
+        if (err_code) {
           return err_code;
         }
         pstr_gain_enc->str_drc_compand[0][j].ch_idx = ch_idx;
diff --git a/encoder/drc_src/impd_drc_gain_calculator.c b/encoder/drc_src/impd_drc_gain_calculator.c
index 2a3400e..bbc5b98 100644
--- a/encoder/drc_src/impd_drc_gain_calculator.c
+++ b/encoder/drc_src/impd_drc_gain_calculator.c
@@ -46,6 +46,7 @@
 #include "impd_drc_gain_enc.h"
 #include "impd_drc_struct_def.h"
 #include "impd_drc_enc.h"
+#include "ixheaace_common_utils.h"
 
 static VOID impd_drc_compand_update_volume(ia_drc_compand_chan_param_struct *pstr_channel_param,
                                            FLOAT64 in_value) {
@@ -68,7 +69,12 @@ static FLOAT64 impd_drc_compand_get_volume(ia_drc_compand_struct *pstr_drc_compa
     return pstr_drc_compand->out_min_lin;
   }
 
-  in_log = log(in_lin);
+  if (fabs(in_lin) <= FLT_EPSILON) {
+    in_log = log(FLT_EPSILON);
+  }
+  else {
+    in_log = log(fabs(in_lin));
+  }
 
   for (idx = 1; idx < pstr_drc_compand->nb_segments; idx++) {
     if (in_log <= pstr_drc_compand->str_segment[idx].x) {
@@ -122,8 +128,6 @@ IA_ERRORCODE impd_drc_td_drc_gain_calc_init(ia_drc_gain_enc_struct *pstr_drc_gai
   pstr_drc_compand =
       &pstr_drc_gain_enc->str_drc_compand[drc_coefficients_uni_drc_idx][gain_set_idx];
 
-  pstr_drc_compand->nb_segments = (pstr_drc_compand->nb_points + 4) * 2;
-
   for (i = 0; i < pstr_drc_compand->nb_points; i++) {
     if (i && pstr_drc_compand->str_segment[2 * ((i - 1) + 1)].x >
                  pstr_drc_compand->str_segment[2 * ((i) + 1)].x) {
@@ -162,6 +166,7 @@ IA_ERRORCODE impd_drc_td_drc_gain_calc_init(ia_drc_gain_enc_struct *pstr_drc_gai
     }
   }
 
+  pstr_drc_compand->nb_segments = num_points * 2;
   for (i = 0; i < pstr_drc_compand->nb_segments; i += 2) {
     pstr_drc_compand->str_segment[i].y += pstr_drc_compand->gain_db;
     pstr_drc_compand->str_segment[i].x *= M_LN10_DIV_20;
@@ -169,35 +174,33 @@ IA_ERRORCODE impd_drc_td_drc_gain_calc_init(ia_drc_gain_enc_struct *pstr_drc_gai
   }
 
   for (i = 4; i < pstr_drc_compand->nb_segments; i += 2) {
-    pstr_drc_compand->str_segment[i - 4].a = 0;
-    pstr_drc_compand->str_segment[i - 4].b =
-        (pstr_drc_compand->str_segment[i - 2].y - pstr_drc_compand->str_segment[i - 4].y) /
-        (pstr_drc_compand->str_segment[i - 2].x - pstr_drc_compand->str_segment[i - 4].x);
-
-    pstr_drc_compand->str_segment[i - 2].a = 0;
-    pstr_drc_compand->str_segment[i - 2].b =
-        (pstr_drc_compand->str_segment[i].y - pstr_drc_compand->str_segment[i - 2].y) /
-        (pstr_drc_compand->str_segment[i].x - pstr_drc_compand->str_segment[i - 2].x);
-
-    theta =
-        atan2(pstr_drc_compand->str_segment[i - 2].y - pstr_drc_compand->str_segment[i - 4].y,
-              pstr_drc_compand->str_segment[i - 2].x - pstr_drc_compand->str_segment[i - 4].x);
-    length =
-        hypot(pstr_drc_compand->str_segment[i - 2].x - pstr_drc_compand->str_segment[i - 4].x,
-              pstr_drc_compand->str_segment[i - 2].y - pstr_drc_compand->str_segment[i - 4].y);
+    FLOAT64 num = 0.0;
+    FLOAT64 den = 0.0f;
 
+    num = pstr_drc_compand->str_segment[i - 2].y - pstr_drc_compand->str_segment[i - 4].y;
+    den = pstr_drc_compand->str_segment[i - 2].x - pstr_drc_compand->str_segment[i - 4].x;
+    length = hypot(num, den);
+    if (length < FLT_EPSILON) {
+      return IA_EXHEAACE_EXE_NONFATAL_USAC_INVALID_GAIN_POINTS;
+    }
+    pstr_drc_compand->str_segment[i - 4].a = 0;
+    pstr_drc_compand->str_segment[i - 4].b = ixheaace_div64(num, den);
+    theta = atan2(num, den);
     r = MIN(radius, length);
     pstr_drc_compand->str_segment[i - 3].x =
         pstr_drc_compand->str_segment[i - 2].x - r * cos(theta);
     pstr_drc_compand->str_segment[i - 3].y =
         pstr_drc_compand->str_segment[i - 2].y - r * sin(theta);
 
-    theta =
-        atan2(pstr_drc_compand->str_segment[i].y - pstr_drc_compand->str_segment[i - 2].y,
-              pstr_drc_compand->str_segment[i - 0].x - pstr_drc_compand->str_segment[i - 2].x);
-    length = hypot(pstr_drc_compand->str_segment[i].x - pstr_drc_compand->str_segment[i - 2].x,
-                   pstr_drc_compand->str_segment[i].y - pstr_drc_compand->str_segment[i - 2].y);
-
+    num = pstr_drc_compand->str_segment[i].y - pstr_drc_compand->str_segment[i - 2].y;
+    den = pstr_drc_compand->str_segment[i].x - pstr_drc_compand->str_segment[i - 2].x;
+    length = hypot(num, den);
+    if (length < FLT_EPSILON) {
+      return IA_EXHEAACE_EXE_NONFATAL_USAC_INVALID_GAIN_POINTS;
+    }
+    pstr_drc_compand->str_segment[i - 2].a = 0;
+    pstr_drc_compand->str_segment[i - 2].b = ixheaace_div64(num, den);
+    theta = atan2(num, den);
     r = MIN(radius, length / 2);
     x = pstr_drc_compand->str_segment[i - 2].x + r * cos(theta);
     y = pstr_drc_compand->str_segment[i - 2].y + r * sin(theta);
@@ -214,9 +217,14 @@ IA_ERRORCODE impd_drc_td_drc_gain_calc_init(ia_drc_gain_enc_struct *pstr_drc_gai
     out_1 = cy - pstr_drc_compand->str_segment[i - 3].y;
     inp_2 = pstr_drc_compand->str_segment[i - 2].x - pstr_drc_compand->str_segment[i - 3].x;
     out_2 = pstr_drc_compand->str_segment[i - 2].y - pstr_drc_compand->str_segment[i - 3].y;
-    pstr_drc_compand->str_segment[i - 3].a = (out_2 / inp_2 - out_1 / inp_1) / (inp_2 - inp_1);
-    pstr_drc_compand->str_segment[i - 3].b =
-        out_1 / inp_1 - pstr_drc_compand->str_segment[i - 3].a * inp_1;
+
+    num = (out_2 * inp_1) - (inp_2 * out_1);
+    den = (inp_2 - inp_1) * inp_1 * inp_2;
+    pstr_drc_compand->str_segment[i - 3].a = ixheaace_div64(num, den);
+
+    num = out_1 - (pstr_drc_compand->str_segment[i - 3].a * inp_1 * inp_1);
+    den = inp_1;
+    pstr_drc_compand->str_segment[i - 3].b = ixheaace_div64(num, den);
   }
   pstr_drc_compand->str_segment[i - 3].x = 0;
   pstr_drc_compand->str_segment[i - 3].y = pstr_drc_compand->str_segment[i - 3].y;
@@ -344,8 +352,6 @@ IA_ERRORCODE impd_drc_stft_drc_gain_calc_init(ia_drc_gain_enc_struct *pstr_drc_g
 
   width_e = (FLOAT32)(pstr_drc_stft_gain_handle->width_db * M_LN10_DIV_20);
 
-  pstr_drc_stft_gain_handle->nb_segments = (pstr_drc_stft_gain_handle->nb_points + 4) * 2;
-
   for (i = 0; i < pstr_drc_stft_gain_handle->nb_points; i++) {
     if (i && pstr_drc_stft_gain_handle->str_segment[2 * ((i - 1) + 1)].x >
                  pstr_drc_stft_gain_handle->str_segment[2 * (i + 1)].x) {
@@ -385,7 +391,7 @@ IA_ERRORCODE impd_drc_stft_drc_gain_calc_init(ia_drc_gain_enc_struct *pstr_drc_g
           pstr_drc_stft_gain_handle->str_segment[2 * (j + 1)];
     }
   }
-
+  pstr_drc_stft_gain_handle->nb_segments = num_points * 2;
   for (i = 0; i < pstr_drc_stft_gain_handle->nb_segments; i += 2) {
     pstr_drc_stft_gain_handle->str_segment[i].y += pstr_drc_stft_gain_handle->gain_db;
     pstr_drc_stft_gain_handle->str_segment[i].x *= M_LN10_DIV_20;
@@ -401,64 +407,31 @@ IA_ERRORCODE impd_drc_stft_drc_gain_calc_init(ia_drc_gain_enc_struct *pstr_drc_g
     numerator = pstr_drc_stft_gain_handle->str_segment[i - 2].y -
                 pstr_drc_stft_gain_handle->str_segment[i - 4].y;
     len = hypot(denominator , numerator);
-    if (len == 0) {
+    if (len < FLT_EPSILON) {
       return IA_EXHEAACE_EXE_NONFATAL_USAC_INVALID_GAIN_POINTS;
     }
-    if (fabs(denominator) < FLT_EPSILON) {
-      if (denominator < 0)
-        denominator = -FLT_EPSILON;
-      else
-        denominator = FLT_EPSILON;
-    }
     pstr_drc_stft_gain_handle->str_segment[i - 4].a = 0;
-    pstr_drc_stft_gain_handle->str_segment[i - 4].b = numerator / denominator;
+    pstr_drc_stft_gain_handle->str_segment[i - 4].b = ixheaace_div64(numerator, denominator);
+    theta = atan2(numerator, denominator);
+    r = MIN(width_e / (2.0f * cos(theta)), len / 2);
+
+    pstr_drc_stft_gain_handle->str_segment[i - 3].x =
+      pstr_drc_stft_gain_handle->str_segment[i - 2].x - r * cos(theta);
+    pstr_drc_stft_gain_handle->str_segment[i - 3].y =
+      pstr_drc_stft_gain_handle->str_segment[i - 2].y - r * sin(theta);
 
     denominator = pstr_drc_stft_gain_handle->str_segment[i].x -
                   pstr_drc_stft_gain_handle->str_segment[i - 2].x;
     numerator = pstr_drc_stft_gain_handle->str_segment[i].y -
                 pstr_drc_stft_gain_handle->str_segment[i - 2].y;
     len = hypot(denominator, numerator);
-    if (len == 0) {
+    if (len < FLT_EPSILON) {
       return IA_EXHEAACE_EXE_NONFATAL_USAC_INVALID_GAIN_POINTS;
     }
-    if (fabs(denominator) < FLT_EPSILON) {
-      if (denominator < 0)
-        denominator = -FLT_EPSILON;
-      else
-        denominator = FLT_EPSILON;
-    }
     pstr_drc_stft_gain_handle->str_segment[i - 2].a = 0;
-    pstr_drc_stft_gain_handle->str_segment[i - 2].b = numerator / denominator;
+    pstr_drc_stft_gain_handle->str_segment[i - 2].b = ixheaace_div64(numerator, denominator);
 
-
-    denominator = pstr_drc_stft_gain_handle->str_segment[i - 2].x -
-                  pstr_drc_stft_gain_handle->str_segment[i - 4].x;
-    numerator = pstr_drc_stft_gain_handle->str_segment[i - 2].y -
-                pstr_drc_stft_gain_handle->str_segment[i - 4].y;
-    if (fabs(denominator) < FLT_EPSILON) {
-      if (denominator < 0)
-        denominator = -FLT_EPSILON;
-      else
-        denominator = FLT_EPSILON;
-    }
     theta = atan2(numerator, denominator);
-    len = hypot(denominator, numerator);
-    r = MIN(width_e / (2.0f * cos(theta)), len / 2);
-
-    pstr_drc_stft_gain_handle->str_segment[i - 3].x =
-        pstr_drc_stft_gain_handle->str_segment[i - 2].x - r * cos(theta);
-    pstr_drc_stft_gain_handle->str_segment[i - 3].y =
-        pstr_drc_stft_gain_handle->str_segment[i - 2].y - r * sin(theta);
-
-    theta = atan2(pstr_drc_stft_gain_handle->str_segment[i].y -
-                      pstr_drc_stft_gain_handle->str_segment[i - 2].y,
-                  pstr_drc_stft_gain_handle->str_segment[i].x -
-                      pstr_drc_stft_gain_handle->str_segment[i - 2].x);
-    len = hypot(pstr_drc_stft_gain_handle->str_segment[i].x -
-                    pstr_drc_stft_gain_handle->str_segment[i - 2].x,
-                pstr_drc_stft_gain_handle->str_segment[i].y -
-                    pstr_drc_stft_gain_handle->str_segment[i - 2].y);
-
     r = MIN(width_e / (2.0f * cos(theta)), len / 2);
     x = pstr_drc_stft_gain_handle->str_segment[i - 2].x + r * cos(theta);
     y = pstr_drc_stft_gain_handle->str_segment[i - 2].y + r * sin(theta);
@@ -479,10 +452,13 @@ IA_ERRORCODE impd_drc_stft_drc_gain_calc_init(ia_drc_gain_enc_struct *pstr_drc_g
             pstr_drc_stft_gain_handle->str_segment[i - 3].x;
     out_2 = pstr_drc_stft_gain_handle->str_segment[i - 2].y -
             pstr_drc_stft_gain_handle->str_segment[i - 3].y;
-    pstr_drc_stft_gain_handle->str_segment[i - 3].a =
-        (out_2 / inp_2 - out_1 / inp_1) / (inp_2 - inp_1);
-    pstr_drc_stft_gain_handle->str_segment[i - 3].b =
-        out_1 / inp_1 - pstr_drc_stft_gain_handle->str_segment[i - 3].a * inp_1;
+    numerator = (out_2 * inp_1) - (inp_2 * out_1);
+    denominator = (inp_2 - inp_1) * inp_2 * inp_1;
+    pstr_drc_stft_gain_handle->str_segment[i - 3].a = ixheaace_div64(numerator, denominator);
+
+    numerator = out_1 - (pstr_drc_stft_gain_handle->str_segment[i - 3].a * inp_1 * inp_1);
+    denominator = inp_1;
+    pstr_drc_stft_gain_handle->str_segment[i - 3].b = ixheaace_div64(numerator, denominator);
   }
   pstr_drc_stft_gain_handle->str_segment[i - 3].x = 0;
   pstr_drc_stft_gain_handle->str_segment[i - 3].y =
diff --git a/encoder/drc_src/impd_drc_gain_enc.c b/encoder/drc_src/impd_drc_gain_enc.c
index fd10488..3ea9cf4 100644
--- a/encoder/drc_src/impd_drc_gain_enc.c
+++ b/encoder/drc_src/impd_drc_gain_enc.c
@@ -21,6 +21,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <math.h>
+#include <float.h>
 #include "ixheaac_type_def.h"
 #include "ixheaac_error_standards.h"
 #include "ixheaace_error_codes.h"
@@ -44,6 +45,7 @@
 #include "ixheaace_sbr_header.h"
 #include "ixheaace_config.h"
 #include "iusace_config.h"
+#include "ixheaace_common_utils.h"
 
 static FLOAT32 impd_drc_limit_drc_gain(const WORD32 gain_coding_profile, const FLOAT32 gain) {
   FLOAT32 limited_drc_gain;
@@ -128,7 +130,7 @@ static VOID impd_drc_check_overshoot(const WORD32 t_gain_step, const FLOAT32 gai
   FLOAT32 k1, k2;
   FLOAT32 slope_norm = 1.0f / (FLOAT32)time_delta_min;
   FLOAT32 margin = 0.2f;
-  FLOAT32 step_inv_2 = 2.0f / t_gain_step;
+  FLOAT32 step_inv_2 = ixheaace_div32(2.0f, (FLOAT32)t_gain_step);
 
   *overshoot_left = FALSE;
   *overshoot_right = FALSE;
@@ -180,7 +182,7 @@ static VOID impd_drc_check_overshoot(const WORD32 t_gain_step, const FLOAT32 gai
   }
 
   if ((!*overshoot_left) && (!*overshoot_right)) {
-    t_gain_step_inv = 1.0f / (FLOAT32)t_gain_step;
+    t_gain_step_inv = ixheaace_div32(1.0f, (FLOAT32)t_gain_step);
     t_gain_step_inv_2 = t_gain_step_inv * t_gain_step_inv;
     k1 = (gain_right - gain_left) * t_gain_step_inv_2;
     k2 = norm_slope_1 + norm_slope_0;
diff --git a/encoder/ixheaace_basic_ops.c b/encoder/ixheaace_basic_ops.c
index 04b727b..a49458e 100644
--- a/encoder/ixheaace_basic_ops.c
+++ b/encoder/ixheaace_basic_ops.c
@@ -49,3 +49,17 @@ FLOAT32 ixheaace_div32(FLOAT32 num, FLOAT32 den) {
     return num / den;
   }
 }
+
+FLOAT64 ixheaace_div64(FLOAT64 num, FLOAT64 den) {
+  if (fabs(den) < FLT_EPSILON) {
+    if (den < 0.0) {
+      return -num;
+    }
+    else {
+      return num;
+    }
+  }
+  else {
+    return num / den;
+  }
+}
diff --git a/encoder/ixheaace_common_utils.h b/encoder/ixheaace_common_utils.h
index 4c03c9f..9609f18 100644
--- a/encoder/ixheaace_common_utils.h
+++ b/encoder/ixheaace_common_utils.h
@@ -38,4 +38,5 @@
 #define C76 (0.5339693427f)   //(sin(u) - 2 * sin(2 * u) - sin(3 * u)) / 3;
 #define C77 (-0.8748422265f)  //(sin(u) + sin(2 * u) + 2 * sin(3 * u)) / 3;
 
-FLOAT32 ixheaace_div32(FLOAT32 num, FLOAT32 den);
\ No newline at end of file
+FLOAT32 ixheaace_div32(FLOAT32 num, FLOAT32 den);
+FLOAT64 ixheaace_div64(FLOAT64 num, FLOAT64 den);