diff options
| author | JP Kobryn <inwardvessel@gmail.com> | 2025-08-06 17:33:50 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-08-28 16:34:32 +0200 |
| commit | e58d219b04d684922ca8afc21adaa185f4729303 (patch) | |
| tree | 480aecaf09a28d303f3a71020b3f910e29ab9cca | |
| parent | f7878d47560d61e3f370aca3cebb8f42a55b990a (diff) | |
cgroup: avoid null de-ref in css_rstat_exit()
commit eea51c6e3f6675b795f6439eaa960eb2948d6905 upstream.
css_rstat_exit() may be called asynchronously in scenarios where preceding
calls to css_rstat_init() have not completed. One such example is this
sequence below:
css_create(...)
{
...
init_and_link_css(css, ...);
err = percpu_ref_init(...);
if (err)
goto err_free_css;
err = cgroup_idr_alloc(...);
if (err)
goto err_free_css;
err = css_rstat_init(css, ...);
if (err)
goto err_free_css;
...
err_free_css:
INIT_RCU_WORK(&css->destroy_rwork, css_free_rwork_fn);
queue_rcu_work(cgroup_destroy_wq, &css->destroy_rwork);
return ERR_PTR(err);
}
If any of the three goto jumps are taken, async cleanup will begin and
css_rstat_exit() will be invoked on an uninitialized css->rstat_cpu.
Avoid accessing the unitialized field by returning early in
css_rstat_exit() if this is the case.
Signed-off-by: JP Kobryn <inwardvessel@gmail.com>
Suggested-by: Michal Koutný <mkoutny@suse.com>
Fixes: 5da3bfa029d68 ("cgroup: use separate rstat trees for each subsystem")
Cc: stable@vger.kernel.org # v6.16
Reported-by: syzbot+8d052e8b99e40bc625ed@syzkaller.appspotmail.com
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | kernel/cgroup/rstat.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/kernel/cgroup/rstat.c b/kernel/cgroup/rstat.c index cbeaa499a96a..408e52d5f7a4 100644 --- a/kernel/cgroup/rstat.c +++ b/kernel/cgroup/rstat.c @@ -488,6 +488,9 @@ void css_rstat_exit(struct cgroup_subsys_state *css) if (!css_uses_rstat(css)) return; + if (!css->rstat_cpu) + return; + css_rstat_flush(css); /* sanity check */ |