cgroup: fix error handling regressions in proc_cgroup_show() and cgroup_release_agent()

4c737b41de7f ("cgroup: make cgroup_path() and friends behave in the
style of strlcpy()") broke error handling in proc_cgroup_show() and
cgroup_release_agent() by not handling negative return values from
cgroup_path_ns_locked().  Fix it.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

1 files changed, 3 insertions, 3 deletions

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 5e2e81ad9175..a7f9fb4e1fc7 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -5781,10 +5781,10 @@ int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns,
                 if (cgroup_on_dfl(cgrp) || !(tsk->flags & PF_EXITING)) {
                         retval = cgroup_path_ns_locked(cgrp, buf, PATH_MAX,
                                                 current->nsproxy->cgroup_ns);
-                        if (retval >= PATH_MAX) {
+                        if (retval >= PATH_MAX)
                                 retval = -ENAMETOOLONG;
+                        if (retval < 0)
                                 goto out_unlock;
-                        }
 
                         seq_puts(m, buf);
                 } else {
@@ -6069,7 +6069,7 @@ static void cgroup_release_agent(struct work_struct *work)
         spin_lock_irq(&css_set_lock);
         ret = cgroup_path_ns_locked(cgrp, pathbuf, PATH_MAX, &init_cgroup_ns);
         spin_unlock_irq(&css_set_lock);
-        if (ret >= PATH_MAX)
+        if (ret < 0 || ret >= PATH_MAX)
                 goto out;
 
         argv[0] = agentbuf;