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From 5a224b981ee32d7cf59aaa9e2c101af65a275edc Mon Sep 17 00:00:00 2001
From: Julien Lepiller <julien@lepiller.eu>
Date: Mon, 20 Feb 2023 19:14:12 +0100
Subject: [PATCH] Dynamically allocate the alternate signal stack.
This patch is a backport of https://github.com/ocaml/ocaml/pull/10266.
---
asmrun/signals_asm.c | 19 +++++++++++--------
1 file changed, 11 insertions(+), 8 deletions(-)
diff --git a/asmrun/signals_asm.c b/asmrun/signals_asm.c
index 3895d75..7e2abe8 100644
--- a/asmrun/signals_asm.c
+++ b/asmrun/signals_asm.c
@@ -182,7 +182,6 @@ DECLARE_SIGNAL_HANDLER(trap_handler)
#ifdef HAS_STACK_OVERFLOW_DETECTION
static char * system_stack_top;
-static char sig_alt_stack[SIGSTKSZ];
#if defined(SYS_linux)
/* PR#4746: recent Linux kernels with support for stack randomization
@@ -274,15 +273,19 @@ void caml_init_signals(void)
#ifdef HAS_STACK_OVERFLOW_DETECTION
{
stack_t stk;
- struct sigaction act;
- stk.ss_sp = sig_alt_stack;
+ stk.ss_sp = malloc(SIGSTKSZ);
stk.ss_size = SIGSTKSZ;
stk.ss_flags = 0;
- SET_SIGACT(act, segv_handler);
- act.sa_flags |= SA_ONSTACK | SA_NODEFER;
- sigemptyset(&act.sa_mask);
- system_stack_top = (char *) &act;
- if (sigaltstack(&stk, NULL) == 0) { sigaction(SIGSEGV, &act, NULL); }
+ if (stk.ss_sp != NULL) {
+ if (sigaltstack(&stk, NULL) != -1) {
+ struct sigaction act;
+ SET_SIGACT(act, segv_handler);
+ act.sa_flags |= SA_ONSTACK | SA_NODEFER;
+ sigemptyset(&act.sa_mask);
+ system_stack_top = (char *) &act;
+ sigaction(SIGSEGV, &act, NULL);
+ }
+ }
}
#endif
}
--
2.38.1
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