From 9d8ae0f7029ba40446ccf45a481b4ec67c204659 Mon Sep 17 00:00:00 2001
From: "Mark A. Grondona" <mgrondona@llnl.gov>
Date: Fri, 7 Oct 2011 10:31:56 -0700
Subject: [PATCH] slurmstepd: Fix race in run_script_as_user
As reported by Sam Lang on slurm-dev, task_epilog scripts are not
held before exec, and thus there is a race condition between when
the task_epilog is launched and slurmstepd calls slurm_container_add()
during which the task_epilog script could either run to completion, or
launch other processes that escape any job container defined by
configuration.
Use the new "exec_wait" api to have the child wait before exec just
as is done in fork_all_tasks.
Based on an original idea by Sam Lang <samlang@gmail.com>.
---
src/slurmd/slurmstepd/mgr.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/src/slurmd/slurmstepd/mgr.c b/src/slurmd/slurmstepd/mgr.c
index 59bbf7322b0..a7da99a185d 100644
--- a/src/slurmd/slurmstepd/mgr.c
+++ b/src/slurmd/slurmstepd/mgr.c
@@ -2183,6 +2183,7 @@ _run_script_as_user(const char *name, const char *path, slurmd_job_t *job,
{
int status, rc, opt;
pid_t cpid;
+ struct exec_wait_info *ei;
xassert(env);
if (path == NULL || path[0] == '\0')
@@ -2199,11 +2200,11 @@ _run_script_as_user(const char *name, const char *path, slurmd_job_t *job,
(slurm_container_create(job) != SLURM_SUCCESS))
error("slurm_container_create: %m");
- if ((cpid = fork()) < 0) {
+ if ((ei = fork_child_with_wait_info(0)) == NULL) {
error ("executing %s: fork: %m", name);
return -1;
}
- if (cpid == 0) {
+ if ((cpid = exec_wait_get_pid (ei)) == 0) {
struct priv_state sprivs;
char *argv[2];
@@ -2230,6 +2231,11 @@ _run_script_as_user(const char *name, const char *path, slurmd_job_t *job,
#else
setpgrp();
#endif
+ /*
+ * Wait for signal from parent
+ */
+ exec_wait_child_wait_for_parent (ei);
+
execve(path, argv, env);
error("execve(): %m");
exit(127);
@@ -2237,6 +2243,11 @@ _run_script_as_user(const char *name, const char *path, slurmd_job_t *job,
if (slurm_container_add(job, cpid) != SLURM_SUCCESS)
error("slurm_container_add: %m");
+
+ if (exec_wait_signal_child (ei) < 0)
+ error ("run_script_as_user: Failed to wakeup %s", name);
+ exec_wait_info_destroy (ei);
+
if (max_wait < 0)
opt = 0;
else
--
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