Fix crash when passing an undersized array to a GLSL array input

panda/src/glstuff/glShaderContext_src.cxx

@@ -1186,6 +1186,7 @@ issue_parameters(int altered) {
       }
 
       GLint p = _glsl_parameter_map[spec._id._seqno];
+      int array_size = min(spec._dim[0], ptr_data->_size / spec._dim[1]);
       switch (spec._type) {
       case Shader::SPT_float:
         {
@@ -1194,16 +1195,16 @@ issue_parameters(int altered) {
           switch (ptr_data->_type) {
           case Shader::SPT_int:
             // Convert int data to float data.
-            data = (float*) alloca(sizeof(float) * spec._dim[0] * spec._dim[1]);
-            for (int i = 0; i < (spec._dim[0] * spec._dim[1]); ++i) {
+            data = (float*) alloca(sizeof(float) * array_size * spec._dim[1]);
+            for (int i = 0; i < (array_size * spec._dim[1]); ++i) {
               data[i] = (float)(((int*)ptr_data->_ptr)[i]);
             }
             break;
 
           case Shader::SPT_double:
             // Downgrade double data to float data.
-            data = (float*) alloca(sizeof(float) * spec._dim[0] * spec._dim[1]);
-            for (int i = 0; i < (spec._dim[0] * spec._dim[1]); ++i) {
+            data = (float*) alloca(sizeof(float) * array_size * spec._dim[1]);
+            for (int i = 0; i < (array_size * spec._dim[1]); ++i) {
               data[i] = (float)(((double*)ptr_data->_ptr)[i]);
             }
             break;
@@ -1217,12 +1218,12 @@ issue_parameters(int altered) {
           }
 
           switch (spec._dim[1]) {
-          case 1: _glgsg->_glUniform1fv(p, spec._dim[0], (float*)data); continue;
-          case 2: _glgsg->_glUniform2fv(p, spec._dim[0], (float*)data); continue;
-          case 3: _glgsg->_glUniform3fv(p, spec._dim[0], (float*)data); continue;
-          case 4: _glgsg->_glUniform4fv(p, spec._dim[0], (float*)data); continue;
-          case 9: _glgsg->_glUniformMatrix3fv(p, spec._dim[0], GL_FALSE, (float*)data); continue;
-          case 16: _glgsg->_glUniformMatrix4fv(p, spec._dim[0], GL_FALSE, (float*)data); continue;
+          case 1: _glgsg->_glUniform1fv(p, array_size, (float*)data); continue;
+          case 2: _glgsg->_glUniform2fv(p, array_size, (float*)data); continue;
+          case 3: _glgsg->_glUniform3fv(p, array_size, (float*)data); continue;
+          case 4: _glgsg->_glUniform4fv(p, array_size, (float*)data); continue;
+          case 9: _glgsg->_glUniformMatrix3fv(p, array_size, GL_FALSE, (float*)data); continue;
+          case 16: _glgsg->_glUniformMatrix4fv(p, array_size, GL_FALSE, (float*)data); continue;
           }
           nassertd(false) continue;
         }
@@ -1239,10 +1240,10 @@ issue_parameters(int altered) {
 
         } else {
           switch (spec._dim[1]) {
-          case 1: _glgsg->_glUniform1iv(p, spec._dim[0], (int*)ptr_data->_ptr); continue;
-          case 2: _glgsg->_glUniform2iv(p, spec._dim[0], (int*)ptr_data->_ptr); continue;
-          case 3: _glgsg->_glUniform3iv(p, spec._dim[0], (int*)ptr_data->_ptr); continue;
-          case 4: _glgsg->_glUniform4iv(p, spec._dim[0], (int*)ptr_data->_ptr); continue;
+          case 1: _glgsg->_glUniform1iv(p, array_size, (int*)ptr_data->_ptr); continue;
+          case 2: _glgsg->_glUniform2iv(p, array_size, (int*)ptr_data->_ptr); continue;
+          case 3: _glgsg->_glUniform3iv(p, array_size, (int*)ptr_data->_ptr); continue;
+          case 4: _glgsg->_glUniform4iv(p, array_size, (int*)ptr_data->_ptr); continue;
           }
           nassertd(false) continue;
         }