From 2be62964c740d453cdfa1ce2f0758948b86ac1ff Mon Sep 17 00:00:00 2001
From: Mark Zhuang <mark.zhuang@spacemit.com>
Date: Thu, 26 Feb 2026 20:06:50 +0800
Subject: [PATCH] Detect exit() from coroutine/fiber alternate stack and
 convert to emu quit

When exit() is called with RSP outside the known main stack range
(emu->init_stack/size_stack), convert to emu->quit instead of killing
the process. This handles custom coroutine libraries that call exit()
as a safety fallback from malloc'd alternate stacks.
---
 src/wrapped/wrappedlibc.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/src/wrapped/wrappedlibc.c b/src/wrapped/wrappedlibc.c
index 83b3c1cce..7cfe69bd8 100644
--- a/src/wrapped/wrappedlibc.c
+++ b/src/wrapped/wrappedlibc.c
@@ -4099,6 +4099,19 @@ EXPORT void my_exit(x64emu_t* emu, int code)
         emu->flags.quitonexit = 2;
         return;
     }
+    if(emu->size_stack && emu->init_stack) {
+        uintptr_t sp = R_RSP;
+        uintptr_t stack_lo = (uintptr_t)emu->init_stack;
+        uintptr_t stack_hi = stack_lo + emu->size_stack;
+        if(sp < stack_lo || sp > stack_hi) {
+            printf_log(LOG_INFO, "exit(%d) called from alternate stack "
+                "(RSP=%p, main stack=%p--%p), converting to emu quit\n",
+                code, (void*)sp, (void*)stack_lo, (void*)stack_hi);
+            emu->quit = 1;
+            R_EAX = code;
+            return;
+        }
+    }
     emu->quit = 1;
     box64_exit_code = code;
     endBox64();