From: "Jiri Slaby (SUSE)" jirislaby@kernel.org

[ Upstream commit 602babaa84d627923713acaf5f7e9a4369e77473 ]

Commit af224ca2df29 (serial: core: Prevent unsafe uart port access, part 3) added few uport == NULL checks. It added one to uart_shutdown(), so the commit assumes, uport can be NULL in there. But right after that protection, there is an unprotected "uart_port_dtr_rts(uport, false);" call. That is invoked only if HUPCL is set, so I assume that is the reason why we do not see lots of these reports.

Or it cannot be NULL at this point at all for some reason :P.

Until the above is investigated, stay on the safe side and move this dereference to the if too.

I got this inconsistency from Coverity under CID 1585130. Thanks.

Signed-off-by: Jiri Slaby (SUSE) jirislaby@kernel.org Cc: Peter Hurley peter@hurleysoftware.com Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Link: https://lore.kernel.org/r/20240805102046.307511-3-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org [Adapted over commit 5701cb8bf50e ("tty: Call ->dtr_rts() parameter active consistently") not in the tree] Signed-off-by: Tomas Krcka krckatom@amazon.de --- drivers/tty/serial/serial_core.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 58e857fb8dee..fd9f635dc247 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -339,14 +339,16 @@ static void uart_shutdown(struct tty_struct *tty, struct uart_state *state) /* * Turn off DTR and RTS early. */ - if (uport && uart_console(uport) && tty) { - uport->cons->cflag = tty->termios.c_cflag; - uport->cons->ispeed = tty->termios.c_ispeed; - uport->cons->ospeed = tty->termios.c_ospeed; - } + if (uport) { + if (uart_console(uport) && tty) { + uport->cons->cflag = tty->termios.c_cflag; + uport->cons->ispeed = tty->termios.c_ispeed; + uport->cons->ospeed = tty->termios.c_ospeed; + }

- if (!tty || C_HUPCL(tty)) - uart_port_dtr_rts(uport, 0); + if (!tty || C_HUPCL(tty)) + uart_port_dtr_rts(uport, 0); + }

uart_port_shutdown(port); }