From 07cb9ef7bc9d4a831d89e6497b44b7221b5f248f Mon Sep 17 00:00:00 2001
From: Dmitry Vyukov <dvyukov@google.com>
Date: Tue, 21 Mar 2023 14:01:54 +0100
Subject: [PATCH] src: don't reset embeder signal handlers

The only bad handler value we can inhert from before exec is SIG_IGN
(any actual function pointer is reset to SIG_DFL during exec).
If that's the case, we want to reset it back to SIG_DFL.
However, it's also possible that an embeder (or an LD_PRELOAD-ed
library) has set up own signal handler for own purposes
(e.g. profiling). If that's the case, keep it intact.

Fix #47013
---
 src/node.cc | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/node.cc b/src/node.cc
index 2aba7333d92513..5874494ba966cc 100644
--- a/src/node.cc
+++ b/src/node.cc
@@ -430,6 +430,18 @@ void ResetSignalHandlers() {
     if (nr == SIGKILL || nr == SIGSTOP)
       continue;
     act.sa_handler = (nr == SIGPIPE || nr == SIGXFSZ) ? SIG_IGN : SIG_DFL;
+    if (act.sa_handler == SIG_DFL) {
+      // The only bad handler value we can inhert from before exec is SIG_IGN
+      // (any actual function pointer is reset to SIG_DFL during exec).
+      // If that's the case, we want to reset it back to SIG_DFL.
+      // However, it's also possible that an embeder (or an LD_PRELOAD-ed
+      // library) has set up own signal handler for own purposes
+      // (e.g. profiling). If that's the case, we want to keep it intact.
+      struct sigaction old;
+      CHECK_EQ(0, sigaction(nr, nullptr, &old));
+      if ((old.sa_flags & SA_SIGINFO) || old.sa_handler != SIG_IGN)
+        continue;
+    }
     CHECK_EQ(0, sigaction(nr, &act, nullptr));
   }
 #endif  // __POSIX__