From 11563e179f2670b0918575e3ba7553c9e27b1aac Mon Sep 17 00:00:00 2001
From: Ben Noordhuis <info@bnoordhuis.nl>
Date: Wed, 14 Jun 2017 12:32:40 +0200
Subject: [PATCH] unix: reset signal mask before execve()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Like the previous commit, except now the signal mask is reset instead
of the signal disposition.  This does open a race window where blocked
signals can get delivered in the interval between the pthread_sigmask()
call and the execve() call (and may end up terminating the process) but
that cannot be helped; the same caveat applies to the previous commit.

Fixes: https://github.com/nodejs/node/issues/13662
PR-URL: https://github.com/libuv/libuv/pull/1376
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Fedor Indutny <fedor.indutny@gmail.com>
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>
Reviewed-By: Saúl Ibarra Corretgé <saghul@gmail.com>
---
 src/unix/process.c | 11 +++++++++++
 test/test-spawn.c  | 12 ++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/src/unix/process.c b/src/unix/process.c
index af44bc5d..80b9686e 100644
--- a/src/unix/process.c
+++ b/src/unix/process.c
@@ -279,8 +279,10 @@ static void uv__process_child_init(const uv_process_options_t* options,
                                    int stdio_count,
                                    int (*pipes)[2],
                                    int error_fd) {
+  sigset_t set;
   int close_fd;
   int use_fd;
+  int err;
   int fd;
   int n;
 
@@ -393,6 +395,15 @@ static void uv__process_child_init(const uv_process_options_t* options,
     _exit(127);
   }
 
+  /* Reset signal mask. */
+  sigemptyset(&set);
+  err = pthread_sigmask(SIG_SETMASK, &set, NULL);
+
+  if (err != 0) {
+    uv__write_int(error_fd, -err);
+    _exit(127);
+  }
+
   execvp(options->file, options->args);
   uv__write_int(error_fd, -errno);
   _exit(127);
diff --git a/test/test-spawn.c b/test/test-spawn.c
index 1ec6bc13..bb35e32b 100644
--- a/test/test-spawn.c
+++ b/test/test-spawn.c
@@ -931,6 +931,12 @@ TEST_IMPL(kill) {
 
   /* Verify that uv_spawn() resets the signal disposition. */
 #ifndef _WIN32
+  {
+    sigset_t set;
+    sigemptyset(&set);
+    sigaddset(&set, SIGTERM);
+    ASSERT(0 == pthread_sigmask(SIG_BLOCK, &set, NULL));
+  }
   ASSERT(SIG_ERR != signal(SIGTERM, SIG_IGN));
 #endif
 
@@ -938,6 +944,12 @@ TEST_IMPL(kill) {
   ASSERT(r == 0);
 
 #ifndef _WIN32
+  {
+    sigset_t set;
+    sigemptyset(&set);
+    sigaddset(&set, SIGTERM);
+    ASSERT(0 == pthread_sigmask(SIG_UNBLOCK, &set, NULL));
+  }
   ASSERT(SIG_ERR != signal(SIGTERM, SIG_DFL));
 #endif