From db49c933fe34a54947dbc7df381fa1700dc1e74f Mon Sep 17 00:00:00 2001
From: Mattias Andrée <m@maandree.se>
Date: Fri, 20 Mar 2026 23:35:38 +0100
Subject: First commit
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Signed-off-by: Mattias Andrée <m@maandree.se>
---
 stackoverflow-recovery.c | 75 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 75 insertions(+)
 create mode 100644 stackoverflow-recovery.c

(limited to 'stackoverflow-recovery.c')

diff --git a/stackoverflow-recovery.c b/stackoverflow-recovery.c
new file mode 100644
index 0000000..436c8c7
--- /dev/null
+++ b/stackoverflow-recovery.c
@@ -0,0 +1,75 @@
+/* See LICENSE file for copyright and license details. */
+#include <setjmp.h>
+#include <signal.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+
+unsigned volatile just_one = 1;
+
+static jmp_buf jmpenv;
+
+
+static void
+sigsegv(int signo)
+{
+	(void) signo;
+
+	siglongjmp(jmpenv, 1);
+}
+
+
+static unsigned
+overflow2(size_t depth)
+{
+	if (!depth)
+		return just_one;
+	depth -= 1u;
+	return overflow2(depth) + overflow2(depth);
+}
+
+
+static unsigned
+overflow(void)
+{
+	return overflow2(SIZE_MAX);
+}
+
+
+int
+main(void)
+{
+	volatile unsigned sum = 0;
+	volatile int i;
+	struct sigaction sa;
+	stack_t ss;
+
+	ss.ss_sp = malloc((size_t)SIGSTKSZ);
+	if (!ss.ss_sp)
+		return 1;
+	ss.ss_size = (size_t)SIGSTKSZ;
+	ss.ss_flags = 0;
+	if (sigaltstack(&ss, NULL))
+		return 2;
+
+	memset(&sa, 0, sizeof(sa));
+	sa.sa_flags = SA_ONSTACK;
+	sa.sa_handler = &sigsegv;
+	sigfillset(&sa.sa_mask);
+	sigaction(SIGSEGV, &sa, NULL);
+
+	for (i = 1; i <= 10; i++) {
+		if (!sigsetjmp(jmpenv, 1)) {
+			printf("%i: before overflow dereference\n", i);
+			sum += overflow();
+		} else {
+			printf("%i: after overflow dereference\n", i);
+		}
+	}
+
+	fflush(stdout);
+	return (int)sum;
+}
-- 
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