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Tue, 17 Feb 2026 10:06:50 -0800 (PST) Received: from tux ([2601:7c0:c37c:4c00:e3a8:26f7:7e08:88e1]) by smtp.gmail.com with ESMTPSA id 00721157ae682-7966c254daasm114839047b3.44.2026.02.17.10.06.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 17 Feb 2026 10:06:50 -0800 (PST) From: Ethan Tidmore To: tglx@kernel.org, peterz@infradead.org Cc: mpe@ellerman.id.au, cai@lca.pw, linux-kernel@vger.kernel.org, Ethan Tidmore Subject: [PATCH] sched/core: Fix error pointer dereference Date: Tue, 17 Feb 2026 12:06:33 -0600 Message-ID: <20260217180633.524129-1-ethantidmore06@gmail.com> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The function idle_thread_get() can return an error pointer and is not checked for one. Add check for error pointer. Detected by Smatch: kernel/cpu.c:911 finish_cpu() error: 'idle' dereferencing possible ERR_PTR() Fixes: bf2c59fce4074 ("sched/core: Fix illegal RCU from offline CPUs") Signed-off-by: Ethan Tidmore Reviewed-by: Vishal Chourasia --- kernel/cpu.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/kernel/cpu.c b/kernel/cpu.c index bc4f7a9ba64e..30af888d1bc1 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -908,7 +908,12 @@ static int bringup_cpu(unsigned int cpu) static int finish_cpu(unsigned int cpu) { struct task_struct *idle =3D idle_thread_get(cpu); - struct mm_struct *mm =3D idle->active_mm; + struct mm_struct *mm; + + if (IS_ERR(idle)) + return PTR_ERR(idle); + + mm =3D idle->active_mm; =20 /* * sched_force_init_mm() ensured the use of &init_mm, --=20 2.53.0