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Mon, 08 Jun 2026 09:52:44 -0700 (PDT) Received: from fx.tailc0aff1.ts.net ([206.206.192.132]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-3074dba046esm15973532eec.9.2026.06.08.09.52.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 08 Jun 2026 09:52:43 -0700 (PDT) From: Weiming Shi To: Greg Kroah-Hartman , Jiri Slaby Cc: linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, Xiang Mei Subject: [PATCH] tty: serial: core: fix NULL pointer deref in uart_resume_port() Date: Mon, 8 Jun 2026 09:52:17 -0700 Message-ID: <20260608165223.70148-1-bestswngs@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit uart_resume_port() looks up the tty device child with device_find_child() and passes the result straight to device_may_wakeup(). device_find_child() returns NULL when the port has no matching tty device child, and device_may_wakeup() dereferences dev->power.can_wakeup, so a NULL tty_dev faults. uart_suspend_port() already guards the same call with "tty_dev && device_may_wakeup(tty_dev)"; the resume path does not. Oops: general protection fault, probably for non-canonical address KASAN: null-ptr-deref in range [0x148-0x14f] RIP: 0010:uart_resume_port (pm_wakeup.h:84 serial_core.c:2477) serial_pnp_resume (8250/8250_pnp.c:522) pnp_bus_resume (drivers/pnp/driver.c:234) Mirror the NULL guard from uart_suspend_port(). put_device(tty_dev) already tolerates a NULL argument, so only the device_may_wakeup() call needs the check; the non-NULL path is unchanged. Fixes: b3b708fa2780 ("wake up from a serial port") Reported-by: Xiang Mei Assisted-by: Claude:claude-opus-4-8 Signed-off-by: Weiming Shi --- drivers/tty/serial/serial_core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 89cebdd278410..7dd3ec3dea438 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -2373,7 +2373,7 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *uport) guard(mutex)(&port->mutex); tty_dev = device_find_child(&uport->port_dev->dev, &match, serial_match_port); - if (!uport->suspended && device_may_wakeup(tty_dev)) { + if (!uport->suspended && tty_dev && device_may_wakeup(tty_dev)) { if (irqd_is_wakeup_set(irq_get_irq_data((uport->irq)))) disable_irq_wake(uport->irq); put_device(tty_dev); -- 2.43.0