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[2a02:3100:a8d0:bc01:6d31:3d12:3a11:d2d0]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-47fd41d1756sm7293694f8f.4.2026.07.31.11.18.54 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Fri, 31 Jul 2026 11:18:55 -0700 (PDT) From: Karl Mehltretter To: Greg Kroah-Hartman , Jiri Slaby Cc: Karl Mehltretter , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v4 3/5] tty: skip cdev_del() when no cdev is registered Date: Fri, 31 Jul 2026 20:18:42 +0200 Message-Id: <20260731181844.11330-4-kmehltretter@gmail.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) In-Reply-To: <20260731181844.11330-1-kmehltretter@gmail.com> References: <20260731181844.11330-1-kmehltretter@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit TTY device registration can fail before a cdev is allocated. Serial core keeps the port so setserial can still use it, and later removal passes the NULL cdev slot to cdev_del(), causing a NULL-pointer dereference. Only delete the cdev when the slot is not NULL. Fixes: a3a10ce3429e ("Avoid usb reset crashes by making tty_io cdevs truly dynamic") Fixes: da4c279942b0 ("serial: enable serdev support") Assisted-by: Claude:claude-fable-5 Signed-off-by: Karl Mehltretter --- drivers/tty/tty_io.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index 6b283fd03ff8..e742bf9d8631 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -3305,7 +3305,7 @@ EXPORT_SYMBOL_GPL(tty_register_device_attr); void tty_unregister_device(struct tty_driver *driver, unsigned index) { device_destroy(&tty_class, MKDEV(driver->major, driver->minor_start) + index); - if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) { + if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC) && driver->cdevs[index]) { cdev_del(driver->cdevs[index]); driver->cdevs[index] = NULL; } -- 2.53.0