Abort on stack overflow instead of re-raising SIGSEGV

src/libstd/sys/unix/stack_overflow.rs

@@ -83,16 +83,19 @@ mod imp {
     // were originally supposed to do.
     //
     // This handler currently exists purely to print an informative message
-    // whenever a thread overflows its stack. When run the handler always
-    // un-registers itself after running and then returns (to allow the original
-    // signal to be delivered again). By returning we're ensuring that segfaults
-    // do indeed look like segfaults.
+    // whenever a thread overflows its stack. We then abort to exit and
+    // indicate a crash, but to avoid a misleading SIGSEGV that might lead
+    // users to believe that unsafe code has accessed an invalid pointer; the
+    // SIGSEGV encountered when overflowing the stack is expected and
+    // well-defined.
     //
-    // Returning from this kind of signal handler is technically not defined to
-    // work when reading the POSIX spec strictly, but in practice it turns out
-    // many large systems and all implementations allow returning from a signal
-    // handler to work. For a more detailed explanation see the comments on
-    // #26458.
+    // If this is not a stack overflow, the handler un-registers itself and
+    // then returns (to allow the original signal to be delivered again).
+    // Returning from this kind of signal handler is technically not defined
+    // to work when reading the POSIX spec strictly, but in practice it turns
+    // out many large systems and all implementations allow returning from a
+    // signal handler to work. For a more detailed explanation see the
+    // comments on #26458.
     unsafe extern fn signal_handler(signum: libc::c_int,
                                     info: *mut libc::siginfo_t,
                                     _data: *mut libc::c_void) {
@@ -102,17 +105,18 @@ mod imp {
         let addr = siginfo_si_addr(info);
 
         // If the faulting address is within the guard page, then we print a
-        // message saying so.
+        // message saying so and abort.
         if guard != 0 && guard - PAGE_SIZE <= addr && addr < guard {
             report_overflow();
+            rtabort!("stack overflow");
+        } else {
+            // Unregister ourselves by reverting back to the default behavior.
+            let mut action: sigaction = mem::zeroed();
+            action.sa_sigaction = SIG_DFL;
+            sigaction(signum, &action, ptr::null_mut());
+
+            // See comment above for why this function returns.
         }
-
-        // Unregister ourselves by reverting back to the default behavior.
-        let mut action: sigaction = mem::zeroed();
-        action.sa_sigaction = SIG_DFL;
-        sigaction(signum, &action, ptr::null_mut());
-
-        // See comment above for why this function returns.
     }
 
     static mut MAIN_ALTSTACK: *mut libc::c_void = ptr::null_mut();

src/rt/rust_test_helpers.c

@@ -158,6 +158,11 @@ rust_get_test_int() {
   return 1;
 }
 
+char *
+rust_get_null_ptr() {
+    return 0;
+}
+
 /* Debug helpers strictly to verify ABI conformance.
  *
  * FIXME (#2665): move these into a testcase when the testsuite

src/test/run-pass/out-of-stack.rs

@@ -12,6 +12,10 @@
 // ignore-musl
 
 #![feature(asm)]
+#![feature(libc)]
+
+#[cfg(unix)]
+extern crate libc;
 
 use std::env;
 use std::process::Command;
@@ -35,6 +39,24 @@ fn loud_recurse() {
     black_box(()); // don't optimize this into a tail call. please.
 }
 
+#[cfg(unix)]
+fn check_status(status: std::process::ExitStatus)
+{
+    use libc;
+    use std::os::unix::process::ExitStatusExt;
+
+    assert!(!status.success());
+    assert!(status.signal() != Some(libc::SIGSEGV)
+            && status.signal() != Some(libc::SIGBUS));
+}
+
+#[cfg(not(unix))]
+fn check_status(status: std::process::ExitStatus)
+{
+    assert!(!status.success());
+}
+
+
 fn main() {
     let args: Vec<String> = env::args().collect();
     if args.len() > 1 && args[1] == "silent" {
@@ -62,7 +84,9 @@ fn main() {
             println!("testing: {}", mode);
 
             let silent = Command::new(&args[0]).arg(mode).output().unwrap();
-            assert!(!silent.status.success());
+
+            check_status(silent.status);
+
             let error = String::from_utf8_lossy(&silent.stderr);
             assert!(error.contains("has overflowed its stack"),
                     "missing overflow message: {}", error);

src/test/run-pass/segfault-no-out-of-stack.rs

@@ -15,18 +15,39 @@ extern crate libc;
 use std::process::{Command, ExitStatus};
 use std::env;
 
+#[link(name = "rust_test_helpers")]
+extern {
+    fn rust_get_null_ptr() -> *mut ::libc::c_char;
+}
+
+#[cfg(unix)]
+fn check_status(status: std::process::ExitStatus)
+{
+    use libc;
+    use std::os::unix::process::ExitStatusExt;
+
+    assert!(status.signal() == Some(libc::SIGSEGV)
+            || status.signal() == Some(libc::SIGBUS));
+}
+
+#[cfg(not(unix))]
+fn check_status(status: std::process::ExitStatus)
+{
+    assert!(!status.success());
+}
+
 fn main() {
     let args: Vec<String> = env::args().collect();
     if args.len() > 1 && args[1] == "segfault" {
-        unsafe { *(0 as *mut isize) = 1 }; // trigger a segfault
+        unsafe { *rust_get_null_ptr() = 1; }; // trigger a segfault
     } else {
         let segfault = Command::new(&args[0]).arg("segfault").output().unwrap();
         let stderr = String::from_utf8_lossy(&segfault.stderr);
         let stdout = String::from_utf8_lossy(&segfault.stdout);
         println!("stdout: {}", stdout);
         println!("stderr: {}", stderr);
         println!("status: {}", segfault.status);
-        assert!(!segfault.status.success());
+        check_status(segfault.status);
         assert!(!stderr.contains("has overflowed its stack"));
     }
 }