Fix stack overflow handling on Unix

src/coreclr/pal/src/exception/seh.cpp

@@ -109,7 +109,7 @@ SEHCleanup()
 {
     TRACE("Cleaning up SEH\n");
 
-    SEHCleanupSignals();
+    SEHCleanupSignals(false /* isChildProcess */);
 }
 
 /*++

src/coreclr/pal/src/exception/signal.cpp

@@ -254,16 +254,15 @@ Function :
     Restore default signal handlers
 
 Parameters :
-    None
-
+    isChildProcess - indicates that it is called from a child process fork
     (no return value)
 
 note :
 reason for this function is that during PAL_Terminate, we reach a point where
 SEH isn't possible anymore (handle manager is off, etc). Past that point,
 we can't avoid crashing on a signal.
 --*/
-void SEHCleanupSignals()
+void SEHCleanupSignals(bool isChildProcess)
 {
     TRACE("Restoring default signal handlers\n");
 
@@ -276,7 +275,16 @@ void SEHCleanupSignals()
         restore_signal(SIGFPE, &g_previous_sigfpe);
         restore_signal(SIGBUS, &g_previous_sigbus);
         restore_signal(SIGABRT, &g_previous_sigabrt);
-        restore_signal(SIGSEGV, &g_previous_sigsegv);
+#if !HAVE_MACH_EXCEPTIONS
+        // Do not restore the sigsegv when stack overflow was hit on a thread,
+        // since all other sigsegvs have to wait in the handler until the process
+        // dies.
+        // If it is called by a forked child though, restore the sigsegv unconditionally
+        if (isChildProcess || (g_stackOverflowHandlerStack != 0)) 
+#endif
+        {
+            restore_signal(SIGSEGV, &g_previous_sigsegv);
+        }
         restore_signal(SIGINT, &g_previous_sigint);
         restore_signal(SIGQUIT, &g_previous_sigquit);
     }

src/coreclr/pal/src/include/pal/signal.hpp

@@ -112,9 +112,11 @@ Function :
     SEHCleanupSignals
 
     Restore default signal handlers
+Parameters :
+    isChildProcess - indicates that it is called from a child process fork
 
-    (no parameters, no return value)
+    (no return value)
 --*/
-void SEHCleanupSignals();
+void SEHCleanupSignals(bool isChildProcess);
 
 #endif /* _PAL_SIGNAL_HPP_ */

src/coreclr/pal/src/thread/process.cpp

@@ -2229,7 +2229,7 @@ PROCCreateCrashDump(
         if (g_createdumpCallback != nullptr)
         {
             // Remove the signal handlers inherited from the runtime process
-            SEHCleanupSignals();
+            SEHCleanupSignals(true /* isChildProcess */);
 
             // Call the statically linked createdump code
             g_createdumpCallback(argv.size(), argv.data());
@@ -2524,7 +2524,7 @@ PROCAbort(int signal, siginfo_t* siginfo)
 
     // Restore all signals; the SIGABORT handler to prevent recursion and
     // the others to prevent multiple core dumps from being generated.
-    SEHCleanupSignals();
+    SEHCleanupSignals(false /* isChildProcess */);
 
     // Abort the process after waiting for the core dump to complete
     abort();

src/tests/baseservices/exceptions/stackoverflow/stackoverflowtester.cs

@@ -4,6 +4,7 @@
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.IO;
+using System.Runtime.InteropServices;
 using System.Text;
 
 namespace TestStackOverflow
@@ -24,12 +25,26 @@ static bool TestStackOverflow(string testName, string testArgs, out List<string>
             testProcess.StartInfo.Arguments = $"{Path.Combine(s_currentPath, "..", testName, $"{testName}.dll")} {testArgs}";
             testProcess.StartInfo.UseShellExecute = false;
             testProcess.StartInfo.RedirectStandardError = true;
+            testProcess.StartInfo.Environment.Add("DOTNET_DbgEnableMiniDump", "0");
+            bool endOfStackTrace = false;
             testProcess.ErrorDataReceived += (sender, line) => 
             {
                 Console.WriteLine($"\"{line.Data}\"");
-                if (!string.IsNullOrEmpty(line.Data))
+                if (!endOfStackTrace && !string.IsNullOrEmpty(line.Data))
                 {
-                    lines.Add(line.Data);
+                    // Store lines only till the end of the stack trace.
+                    // In the CI it can also contain lines with createdump info.
+                    if (line.Data.StartsWith("Stack overflow.") ||
+                        line.Data.StartsWith("Repeat ") ||
+                        line.Data.StartsWith("------") ||
+                        line.Data.StartsWith("   at "))
+                    {
+                        lines.Add(line.Data);
+                    }
+                    else
+                    {
+                        endOfStackTrace = true;
+                    }
                 }
             };
 
@@ -256,24 +271,28 @@ static int Main()
                 return 101;
             }
 
-            if (!TestStackOverflowLargeFrameMainThread())
-            {
-                return 102;
-            }
-
             if (!TestStackOverflowSmallFrameSecondaryThread())
             {
                 return 103;
             }
 
-            if (!TestStackOverflowLargeFrameSecondaryThread())
+            if ((RuntimeInformation.ProcessArchitecture != Architecture.Arm64) ||
+                ((Environment.OSVersion.Platform != PlatformID.Unix) && (Environment.OSVersion.Platform != PlatformID.MacOSX)))
             {
-                return 104;
-            }
+                if (!TestStackOverflowLargeFrameMainThread())
+                {
+                    return 102;
+                }
 
-            if (!TestStackOverflow3())
-            {
-                return 105;
+                if (!TestStackOverflowLargeFrameSecondaryThread())
+                {
+                    return 104;
+                }
+
+                if (!TestStackOverflow3())
+                {
+                    return 105;
+                }
             }
 
             return 100;

src/tests/issues.targets

@@ -86,9 +86,6 @@
 
     <!-- All Unix targets  on CoreCLR Runtime -->
     <ItemGroup Condition="'$(XunitTestBinBase)' != '' and '$(TargetsWindows)' != 'true' and '$(RuntimeFlavor)' == 'coreclr' ">
-        <ExcludeList Include="$(XunitTestBinBase)/baseservices/exceptions/stackoverflow/stackoverflowtester/*">
-            <Issue>https://github.com/dotnet/runtime/issues/46175</Issue>
-        </ExcludeList>
         <ExcludeList Include="$(XunitTestBinBase)/tracing/eventpipe/eventsourceerror/eventsourceerror/*">
             <Issue>https://github.com/dotnet/runtime/issues/80666</Issue>
         </ExcludeList>