Messages in this thread Patch in this message | | | From | Michael Thalmeier <> | Subject | [PATCH] tty: ttynull: implement console write | Date | Tue, 14 Feb 2023 11:23:17 +0100 |
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Since commit 3579b59c7edc475013ae769a2d26d99733c95f13 ("printk: refactor and rework printing logic"), con->write is called without checking if it is implemented in the console driver. This does make some sense, because for all "normal" consoles it is vital to have a write function. As the ttynull console driver does not need any console output the write function was not implemented. This caused a "unable to handle kernel NULL pointer dereference" when the write function is called now.
To fix this issue, implement an empty write function.
Signed-off-by: Michael Thalmeier <michael.thalmeier@hale.at> Cc: stable@vger.kernel.org --- drivers/tty/ttynull.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/drivers/tty/ttynull.c b/drivers/tty/ttynull.c index 1d4438472442..6e9323544a7d 100644 --- a/drivers/tty/ttynull.c +++ b/drivers/tty/ttynull.c @@ -40,6 +40,12 @@ static unsigned int ttynull_write_room(struct tty_struct *tty) return 65536; } + +static void ttynull_console_write(struct console *co, const char *buf, + unsigned count) +{ +} + static const struct tty_operations ttynull_ops = { .open = ttynull_open, .close = ttynull_close, @@ -56,6 +62,7 @@ static struct tty_driver *ttynull_device(struct console *c, int *index) static struct console ttynull_console = { .name = "ttynull", + .write = ttynull_console_write, .device = ttynull_device, }; -- 2.39.1
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