From 883d68803d17d6f64cdabf2c8ef846345e2d0094 Mon Sep 17 00:00:00 2001
From: Julien Lepiller <julien@lepiller.eu>
Date: Sun, 19 Feb 2023 10:20:19 +0100
Subject: [PATCH] Dynamically allocate the alternate signal stack.

This patch is a backport of https://github.com/ocaml/ocaml/pull/10266.
---
 ocaml-src/asmrun/signals_asm.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/ocaml-src/asmrun/signals_asm.c b/ocaml-src/asmrun/signals_asm.c
index 3895d75..d37b481 100644
--- a/ocaml-src/asmrun/signals_asm.c
+++ b/ocaml-src/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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<div class='path'>path: <a href='/guix/log/?id=ca7e310f7ac32354b2e693e9a0f783320952a8fc'>root</a>/<a href='/guix/log/gnu?id=ca7e310f7ac32354b2e693e9a0f783320952a8fc'>gnu</a>/<a href='/guix/log/gnu/packages?id=ca7e310f7ac32354b2e693e9a0f783320952a8fc'>packages</a>/<a href='/guix/log/gnu/packages/patches?id=ca7e310f7ac32354b2e693e9a0f783320952a8fc'>patches</a>/<a href='/guix/log/gnu/packages/patches/shakespeare-spl-fix-grammar.patch?id=ca7e310f7ac32354b2e693e9a0f783320952a8fc'>shakespeare-spl-fix-grammar.patch</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/packages/patches/shakespeare-spl-fix-grammar.patch?id=ca7e310f7ac32354b2e693e9a0f783320952a8fc&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-12-29 13:54:48 +0100'>2020-12-29</span></td><td><a href='/guix/commit/gnu/packages/patches/shakespeare-spl-fix-grammar.patch?id=142f8713ab647ecb8833dcf9eb98e3bdc62cd44a'>gnu: Add shakespeare-spl.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/patches/shakespeare-spl-fix-grammar.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it here.
* gnu/packages/esolangs.scm (shakespeare-spl): New variable.
</span></span></td><td>Leo Prikler</td></tr>