fix: Fix five bugs - critical stability and moderate security issues

Fixed three critical division by zero bugs and two moderate bugs:

1. Wall model convergence - zero-check before division (wall_model.cpp:312)
2. Wall model Gamma - epsilon check for exp(1/Gamma) (wall_model.cpp:398)
3. Radiation emissivity - clamp to [0,1] range (CRadP1Solver.cpp:286,360,434)
4. Restart metadata - correct ITER= offset 9→5 (CSolver.cpp:3386)
5. Filename buffer - replace strcpy with strncpy (CPhysicalGeometry.cpp:8255,8569)

Improves solver stability, correctness, and security.

Signed-off-by: shbhmexe <[email protected]>

Author: shbhmexe

Common/src/geometry/CPhysicalGeometry.cpp

@@ -8252,7 +8252,8 @@ void CPhysicalGeometry::SetSensitivity(CConfig* config) {
 
     char str_buf[CGNS_STRING_SIZE], fname[100];
     unsigned short iVar;
-    strcpy(fname, filename.c_str());
+    strncpy(fname, filename.c_str(), sizeof(fname) - 1);
+    fname[sizeof(fname) - 1] = '\0';  // Ensure null termination
     int nRestart_Vars = 5, nFields;
     int* Restart_Vars = new int[5];
     passivedouble* Restart_Data = nullptr;
@@ -8565,7 +8566,8 @@ void CPhysicalGeometry::SetSensitivity(CConfig* config) {
     /*--- First, check that this is not a binary restart file. ---*/
 
     char fname[100];
-    strcpy(fname, filename.c_str());
+    strncpy(fname, filename.c_str(), sizeof(fname) - 1);
+    fname[sizeof(fname) - 1] = '\0';  // Ensure null termination
     int magic_number;
 
 #ifndef HAVE_MPI

Common/src/wall_model.cpp

@@ -307,8 +307,12 @@ void CWallModel1DEQ::WallShearStressAndHeatFlux(const su2double tExchange, const
       SU2_MPI::Error("Y+ greater than one: Increase the number of points or growth ratio.", CURRENT_FUNCTION);
 
     /* Define a norm
+     * Check convergence only if previous values are non-zero to avoid division by zero
      */
-    if (abs(1.0 - tauWall / tauWall_prev) < tol && abs(1.0 - qWall / qWall_prev) < tol) {
+    bool tau_converged = (tauWall_prev != 0.0) ? (abs(1.0 - tauWall / tauWall_prev) < tol) : false;
+    bool q_converged = (qWall_prev != 0.0) ? (abs(1.0 - qWall / qWall_prev) < tol) : false;
+
+    if (tau_converged && q_converged) {
       converged = true;
     }
   }
@@ -390,9 +394,20 @@ void CWallModelLogLaw::WallShearStressAndHeatFlux(const su2double tExchange, con
     const su2double lhs = -((tExchange - TWall) * rho_wall * c_p * u_tau);
     const su2double Gamma = -(0.01 * (Pr_lam * pow(y_plus, 4.0)) / (1.0 + 5.0 * y_plus * pow(Pr_lam, 3.0)));
     const su2double rhs_1 = Pr_lam * y_plus * exp(Gamma);
+    
+    /* Protect against division by zero in exp(1/Gamma) when Gamma is very small */
+    const su2double eps_gamma = 1e-20;
+    su2double exp_term;
+    if (abs(Gamma) > eps_gamma) {
+      exp_term = exp(1.0 / Gamma);
+    } else {
+      /* For very small Gamma, cap the exponential to prevent overflow/division by zero */
+      exp_term = (Gamma > 0) ? exp(1.0 / eps_gamma) : exp(-1.0 / eps_gamma);
+    }
+    
     const su2double rhs_2 =
         (2.12 * log(1.0 + y_plus) + pow((3.85 * pow(Pr_lam, (1.0 / 3.0)) - 1.3), 2.0) + 2.12 * log(Pr_lam)) *
-        exp(1. / Gamma);
+        exp_term;
     qWall = lhs / (rhs_1 + rhs_2);
   } else {
     qWall = Wall_HeatFlux;

SU2_CFD/src/solvers/CRadP1Solver.cpp

@@ -282,6 +282,10 @@ void CRadP1Solver::BC_Isothermal_Wall(CGeometry *geometry, CSolver **solver_cont
   /*--- Get the specified wall emissivity from config ---*/
   Wall_Emissivity = config->GetWall_Emissivity(Marker_Tag);
 
+  /*--- Clamp emissivity to valid physical range [0,1] to prevent division by zero ---*/
+  if (Wall_Emissivity < 0.0) Wall_Emissivity = 0.0;
+  if (Wall_Emissivity > 1.0) Wall_Emissivity = 1.0;
+
   /*--- Compute the constant for the wall theta ---*/
   Theta = Wall_Emissivity / (2.0*(2.0 - Wall_Emissivity));
 
@@ -356,6 +360,10 @@ void CRadP1Solver::BC_Far_Field(CGeometry *geometry, CSolver **solver_container,
   /*--- Get the specified wall emissivity from config ---*/
   Wall_Emissivity = config->GetWall_Emissivity(Marker_Tag);
 
+  /*--- Clamp emissivity to valid physical range [0,1] to prevent division by zero ---*/
+  if (Wall_Emissivity < 0.0) Wall_Emissivity = 0.0;
+  if (Wall_Emissivity > 1.0) Wall_Emissivity = 1.0;
+
   /*--- Compute the constant for the wall theta ---*/
   Theta = Wall_Emissivity / (2.0*(2.0 - Wall_Emissivity));
 
@@ -430,6 +438,10 @@ void CRadP1Solver::BC_Marshak(CGeometry *geometry, CSolver **solver_container, C
   /*--- Get the specified wall emissivity from config ---*/
   Wall_Emissivity = config->GetWall_Emissivity(Marker_Tag);
 
+  /*--- Clamp emissivity to valid physical range [0,1] to prevent division by zero ---*/
+  if (Wall_Emissivity < 0.0) Wall_Emissivity = 0.0;
+  if (Wall_Emissivity > 1.0) Wall_Emissivity = 1.0;
+
   /*--- Compute the constant for the wall theta ---*/
   Theta = Wall_Emissivity / (2.0*(2.0 - Wall_Emissivity));
 

SU2_CFD/src/solvers/CSolver.cpp

@@ -3383,8 +3383,7 @@ void CSolver::Read_SU2_Restart_Metadata(CGeometry *geometry, CConfig *config, bo
 
       position = text_line.find ("ITER=",0);
       if (position != string::npos) {
-        // TODO: 'ITER=' has 5 chars, not 9!
-        text_line.erase (0,9); InnerIter_ = atoi(text_line.c_str());
+        text_line.erase (0,5); InnerIter_ = atoi(text_line.c_str());  // 'ITER=' has 5 chars
       }
 
       /*--- Angle of attack ---*/