[CRIU] [PATCH 2/2] restore: block sigchld to remap task_entries

[Andrei Vagin]

From: Andrei Vagin <avagin at virtuozzo.com>

Currently we remap task_entries but it can be used from a sigchld hanler.
We need to block sigchld to remap task_entries and unlock it
when a restorer sigchld handler is set.

Signed-off-by: Andrei Vagin <avagin at virtuozzo.com>
---
 criu/cr-restore.c   | 11 +++++++++++
 criu/pie/restorer.c |  4 ++++
 2 files changed, 15 insertions(+)

diff --git a/criu/cr-restore.c b/criu/cr-restore.c
index 8da8ab2..a0e16ee 100644
--- a/criu/cr-restore.c
+++ b/criu/cr-restore.c
@@ -2868,6 +2868,8 @@ static int sigreturn_restore(pid_t pid, struct task_restore_args *task_args, uns
 	unsigned long creds_pos = 0;
 	unsigned long creds_pos_next;
 
+	sigset_t blockmask;
+
 	pr_info("Restore via sigreturn\n");
 
 	/* pr_info_vma_list(&self_vma_list); */
@@ -3000,6 +3002,15 @@ static int sigreturn_restore(pid_t pid, struct task_restore_args *task_args, uns
 	}
 
 	task_args->breakpoint = &rsti(current)->breakpoint;
+
+	sigemptyset(&blockmask);
+	sigaddset(&blockmask, SIGCHLD);
+
+	if (sigprocmask(SIG_BLOCK, &blockmask, NULL) == -1) {
+		pr_perror("Can not set mask of blocked signals");
+		return -1;
+	}
+
 	task_args->task_entries = rst_mem_remap_ptr(task_entries_pos, RM_SHREMAP);
 
 	task_args->premmapped_addr = (unsigned long)rsti(current)->premmapped_addr;
diff --git a/criu/pie/restorer.c b/criu/pie/restorer.c
index 4a96c7e..ac0f475 100644
--- a/criu/pie/restorer.c
+++ b/criu/pie/restorer.c
@@ -1132,6 +1132,10 @@ long __export_restore_task(struct task_restore_args *args)
 	act.rt_sa_restorer = cr_restore_rt;
 	sys_sigaction(SIGCHLD, &act, NULL, sizeof(k_rtsigset_t));
 
+	ksigfillset(&to_block);
+	ksigaddset(&to_block, SIGCHLD);
+	ret = sys_sigprocmask(SIG_UNBLOCK, &to_block, NULL, sizeof(k_rtsigset_t));
+
 	log_set_fd(args->logfd);
 	log_set_loglevel(args->loglevel);
 
-- 
2.7.4