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Thu, 31 Jul 2025 12:29:11 -0700 (PDT) Received: from jpkobryn-fedora-PF5CFKNC.lan ([73.222.117.172]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-241d1f0f603sm24824735ad.48.2025.07.31.12.29.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 31 Jul 2025 12:29:11 -0700 (PDT) From: JP Kobryn To: tj@kernel.org, shakeel.butt@linux.dev, mkoutny@suse.com, yosryahmed@google.com, hannes@cmpxchg.org, akpm@linux-foundation.org Cc: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, kernel-team@meta.com Subject: [PATCH cgroup/for-6.16-fixes] cgroup: avoid null de-ref in css_rstat_exit() Date: Thu, 31 Jul 2025 12:27:34 -0700 Message-ID: <20250731192734.106214-1-inwardvessel@gmail.com> X-Mailer: git-send-email 2.50.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable This function may be called asynchronously in scenarios where preceding calls to css_rstat_init() have not completed. Return early in this case. Signed-off-by: JP Kobryn Suggested-by: Michal Koutn=C3=BD Fixes: 5da3bfa029d68 ("cgroup: use separate rstat trees for each subsystem") Reported-by: syzbot+8d052e8b99e40bc625ed@syzkaller.appspotmail.com Acked-by: Shakeel Butt --- kernel/cgroup/rstat.c | 3 +++ 1 file changed, 3 insertions(+) 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; =20 + if (!css->rstat_cpu) + return; + css_rstat_flush(css); =20 /* sanity check */ --=20 2.47.3