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

stable inclusion from stable-v6.6.57 commit e418d91195d29d5f9c9685ff309b92b04b41dc40 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAYREU CVE: CVE-2024-50058

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

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[ 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 Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Yi Yang yiyang13@huawei.com --- 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 5d5570bebfeb..8ff0efac6aa0 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -374,14 +374,16 @@ 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, false); + if (!tty || C_HUPCL(tty)) + uart_port_dtr_rts(uport, false); + }

uart_port_shutdown(port); }