From 95f5016955e519c392c746e38e0c9460f2c1aa0c Mon Sep 17 00:00:00 2001
From: Julien Lepiller <julien@lepiller.eu>
Date: Sun, 19 Feb 2023 09:58:57 +0100
Subject: [PATCH] Dynamically allocate the alternate signal stack.

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

diff --git a/runtime/signals_nat.c b/runtime/signals_nat.c
index 29a5f49..a193fc2 100644
--- a/runtime/signals_nat.c
+++ b/runtime/signals_nat.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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<tr><td><span title='2023-05-31 17:23:21 +0200'>2023-05-31</span></td><td><a href='/guix/commit/po/packages/fa.po?id=8e9e6a6482f3ba98d1cdcad344ee488e8751fee7'>nls: Update translations.</a><span class='msg-avail'>...<span class='msg-tooltip'>* doc/guix-cookbook.texi (Top): Mention Slovak.
</span></span></td><td>Florian Pelz</td></tr>
<tr><td><span title='2023-03-07 21:14:57 +0100'>2023-03-07</span></td><td><a href='/guix/commit/po/packages/fa.po?id=d333958763b0840c4cd895601b079b68358a6a46'>nls: Update translations.</a></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2023-01-05 08:14:55 +0100'>2023-01-05</span></td><td><a href='/guix/commit/po/packages/fa.po?id=dc7eb6f07ae982b4c9d083cfb10f72cb031c0424'>nls: Update translations.</a><span class='msg-avail'>...<span class='msg-tooltip'>* po/guix/ka.po: New file.
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* po/packages/uk.po: New file.
* po/packages/LINGUAS: Add it.
</span></span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2022-12-04 22:25:23 +0100'>2022-12-04</span></td><td><a href='/guix/commit/po/packages/fa.po?id=2e75b328b6bbdadbffe5b643a4891b5026a0defd'>nls: Update translations.</a><span class='msg-avail'>...<span class='msg-tooltip'>po/packages/vi.po: New file.
po/packages/LINGUAS: Add it.
</span></span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2022-11-04 10:56:38 +0100'>2022-11-04</span></td><td><a href='/guix/commit/po/packages/fa.po?id=a65ce9dd500460af4f97e7398fb35dd817f4c677'>nls: Update translations.</a><span class='msg-avail'>...<span class='msg-tooltip'>* po/guix/lt.po: New file.
* po/guix/LINGUAS: Add lt.
</span></span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2022-10-06 08:20:20 +0200'>2022-10-06</span></td><td><a href='/guix/commit/po/packages/fa.po?id=70fc8f6d619ce9f16a8cc0bbb10a011bd3a9997a'>nls: Update translations.</a></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2022-09-04 16:52:02 +0200'>2022-09-04</span></td><td><a href='/guix/commit/po/packages/fa.po?id=77e3042aef6d8e519d016555464e466399318b4f'>nls: Update translations.</a></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2022-08-10 23:32:24 +0200'>2022-08-10</span></td><td><a href='/guix/commit/po/packages/fa.po?id=aacbe59fbceb8a93ecb68fed8581dfdd70dafc11'>nls: Update translations.</a><span class='msg-avail'>...<span class='msg-tooltip'>po/guix/bn.po: New file.
po/guix/LINGUAS: Add it.
</span></span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2022-07-09 21:49:34 +0200'>2022-07-09</span></td><td><a href='/guix/commit/po/packages/fa.po?id=e0d47d8facafb6d6c04741bbf30eefbc68aaefb9'>nls: Update translations.</a><span class='msg-avail'>...<span class='msg-tooltip'>po/guix/tr.po: New file.
po/guix/LINGUAS: Add it.
</span></span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2022-06-04 17:42:54 +0200'>2022-06-04</span></td><td><a href='/guix/commit/po/packages/fa.po?id=809c57c872a6dd48007d1abf6d7f3dd1482ec53a'>nls: Update translations.</a><span class='msg-avail'>...<span class='msg-tooltip'>po/packages/tr.po: New file.
po/packages/LINGUAS: Add it.
</span></span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2022-05-01 18:07:34 +0200'>2022-05-01</span></td><td><a href='/guix/commit/po/packages/fa.po?id=6b4124cdcc203d47dc40158062afa1497d73d592'>nls: Update translations.</a><span class='msg-avail'>...<span class='msg-tooltip'>po/guix/ja.po: New file.
po/guix/LINGUAS: Add it.
</span></span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2022-04-02 18:42:36 +0200'>2022-04-02</span></td><td><a href='/guix/commit/po/packages/fa.po?id=8a208df17fe81fbf34f5a86cc52bb0b8e33c7b96'>nls: Update translations.</a><span class='msg-avail'>...<span class='msg-tooltip'>* po/packages/fi.po: New file.
* po/packages/LINGUAS: Add it.
</span></span></td><td>Julien Lepiller</td></tr>