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serial: protect uart_port_dtr_rts() in uart_shutdown() too

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[ Upstream commit 602babaa84d627923713acaf5f7e9a4369e77473 ]

Commit af224ca2df (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 5701cb8bf5 ("tty: Call ->dtr_rts() parameter
active consistently") not in the tree]
Signed-off-by: Tomas Krcka <krckatom@amazon.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Jiri Slaby (SUSE)
2024-10-25 11:05:48 +00:00
committed by Greg Kroah-Hartman
parent 8251093971
commit d7b5876a6e
1 changed files with 9 additions and 7 deletions
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16
drivers/tty/serial/serial_core.c
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@@ -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);
}