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([66.170.99.2]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2d85b3b95e8sm8511509a91.54.2024.09.02.01.35.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Sep 2024 01:35:36 -0700 (PDT) From: Vamsi Krishna Brahmajosyula To: stable@vger.kernel.org, gregkh@linuxfoundation.org Cc: paulmck@kernel.org, frederic@kernel.org, neeraj.upadhyay@kernel.org, joel@joelfernandes.org, josh@joshtriplett.org, boqun.feng@gmail.com, urezki@gmail.com, rostedt@goodmis.org, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, qiang.zhang1211@gmail.com, rcu@vger.kernel.org, linux-kernel@vger.kernel.org, ajay.kaher@broadcom.com, alexey.makhalov@broadcom.com, vasavi.sirnapalli@broadcom.com, Nikita Kiryushin , Sasha Levin , Vamsi Krishna Brahmajosyula Subject: [PATCH v5.10-v5.15] rcu-tasks: Fix show_rcu_tasks_trace_gp_kthread buffer overflow Date: Mon, 2 Sep 2024 03:33:55 -0500 Message-ID: <20240902083422.1095022-2-vamsi-krishna.brahmajosyula@broadcom.com> X-Mailer: git-send-email 2.45.2 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" From: Nikita Kiryushin [ Upstream commit cc5645fddb0ce28492b15520306d092730dffa48 ] There is a possibility of buffer overflow in show_rcu_tasks_trace_gp_kthread() if counters, passed to sprintf() are huge. Counter numbers, needed for this are unrealistically high, but buffer overflow is still possible. Use snprintf() with buffer size instead of sprintf(). Found by Linux Verification Center (linuxtesting.org) with SVACE. Fixes: edf3775f0ad6 ("rcu-tasks: Add count for idle tasks on offline CPUs") Signed-off-by: Nikita Kiryushin Reviewed-by: Steven Rostedt (Google) Signed-off-by: Paul E. McKenney Signed-off-by: Uladzislau Rezki (Sony) Signed-off-by: Sasha Levin Signed-off-by: Vamsi Krishna Brahmajosyula --- kernel/rcu/tasks.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h index 105fdc2bb004..bede3a4f108e 100644 --- a/kernel/rcu/tasks.h +++ b/kernel/rcu/tasks.h @@ -1240,7 +1240,7 @@ static void show_rcu_tasks_trace_gp_kthread(void) { char buf[64]; =20 - sprintf(buf, "N%d h:%lu/%lu/%lu", atomic_read(&trc_n_readers_need_end), + snprintf(buf, sizeof(buf), "N%d h:%lu/%lu/%lu", atomic_read(&trc_n_reader= s_need_end), data_race(n_heavy_reader_ofl_updates), data_race(n_heavy_reader_updates), data_race(n_heavy_reader_attempts)); --=20 2.45.2