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[69.172.89.235]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-c79218fc64csm9648912a12.11.2026.04.13.01.45.52 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Mon, 13 Apr 2026 01:45:53 -0700 (PDT) From: Dudu Lu To: linux-can@vger.kernel.org Cc: robin@protonic.nl, o.rempel@pengutronix.de, Dudu Lu Subject: [PATCH] can: j1939: Use hrtimer_cancel in j1939_cancel_active_session Date: Mon, 13 Apr 2026 16:45:48 +0800 Message-Id: <20260413084548.69294-1-phx0fer@gmail.com> X-Mailer: git-send-email 2.39.3 (Apple Git-145) Precedence: bulk X-Mailing-List: linux-can@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit j1939_cancel_active_session() uses hrtimer_try_to_cancel() for both txtimer and rxtimer. When hrtimer_try_to_cancel() returns -1, it means the timer callback is currently executing. In this case, the function neither cancels the timer nor drops the session reference via j1939_session_put(). The session is then deactivated while the timer callback may still be running, leading to a potential use-after-free if the callback accesses the session after it has been cleaned up. Replace hrtimer_try_to_cancel() with hrtimer_cancel() which will wait for an in-progress callback to complete before returning, ensuring the timer is fully stopped before the session is deactivated. Note: This changes the function to potentially sleep (hrtimer_cancel waits for the callback). The function is called with active_session_list_lock held (a spinlock), so an alternative approach would be to handle the -1 return from hrtimer_try_to_cancel() without blocking. However, if the lock can be converted or the cancel moved outside the lock, hrtimer_cancel() is the cleaner fix. Signed-off-by: Dudu Lu --- net/can/j1939/transport.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c index df93d57907da..996d4c2cbbb0 100644 --- a/net/can/j1939/transport.c +++ b/net/can/j1939/transport.c @@ -2230,9 +2230,9 @@ int j1939_cancel_active_session(struct j1939_priv *priv, struct sock *sk) &priv->active_session_list, active_session_list_entry) { if (!sk || sk == session->sk) { - if (hrtimer_try_to_cancel(&session->txtimer) == 1) + if (hrtimer_cancel(&session->txtimer)) j1939_session_put(session); - if (hrtimer_try_to_cancel(&session->rxtimer) == 1) + if (hrtimer_cancel(&session->rxtimer)) j1939_session_put(session); session->err = ESHUTDOWN; -- 2.39.3 (Apple Git-145)