2021-12-07 22:18:22

by Vihas Makwana

Subject: [PATCH] tty: serial: return appropriate error on failure

when a user with CAP_SYS_ADMIN disabled calls ioctl (TIOCSSERIAL),
uart_set_info() returns 0 instead of -EPERM and the user remains unware
about what went wrong. Fix this.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=215205

Signed-off-by: Vihas Mak <[email protected]>
---
drivers/tty/serial/serial_core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 61e3dd022..c204bdecc 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -960,7 +960,7 @@ static int uart_set_info(struct tty_struct *tty, struct tty_port *port,
uport->fifosize = new_info->xmit_fifo_size;

check_and_exit:
- retval = 0;
+ retval = retval < 0 ? retval : 0;
if (uport->type == PORT_UNKNOWN)
goto exit;
if (tty_port_initialized(port)) {
--
2.30.2

2021-12-08 05:44:58

by Jiri Slaby

Subject: Re: [PATCH] tty: serial: return appropriate error on failure

On 07. 12. 21, 23:17, Vihas Mak wrote:
> when a user with CAP_SYS_ADMIN disabled calls ioctl (TIOCSSERIAL),
> uart_set_info() returns 0 instead of -EPERM and the user remains unware
> about what went wrong. Fix this.
>
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=215205
>
> Signed-off-by: Vihas Mak <[email protected]>
> ---
> drivers/tty/serial/serial_core.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
> index 61e3dd022..c204bdecc 100644
> --- a/drivers/tty/serial/serial_core.c
> +++ b/drivers/tty/serial/serial_core.c
> @@ -960,7 +960,7 @@ static int uart_set_info(struct tty_struct *tty, struct tty_port *port,
> uport->fifosize = new_info->xmit_fifo_size;
>
> check_and_exit:
> - retval = 0;
> + retval = retval < 0 ? retval : 0;

This is wrong IMO. See:
https://bugzilla.kernel.org/show_bug.cgi?id=215205#c1

> if (uport->type == PORT_UNKNOWN)
> goto exit;
> if (tty_port_initialized(port)) {
>


--
js
suse labs

2021-12-08 05:45:11

by Greg Kroah-Hartman

Subject: Re: [PATCH] tty: serial: return appropriate error on failure

On Wed, Dec 08, 2021 at 03:47:41AM +0530, Vihas Mak wrote:
> when a user with CAP_SYS_ADMIN disabled calls ioctl (TIOCSSERIAL),
> uart_set_info() returns 0 instead of -EPERM and the user remains unware
> about what went wrong. Fix this.
>
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=215205
>
> Signed-off-by: Vihas Mak <[email protected]>
> ---
> drivers/tty/serial/serial_core.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
> index 61e3dd022..c204bdecc 100644
> --- a/drivers/tty/serial/serial_core.c
> +++ b/drivers/tty/serial/serial_core.c
> @@ -960,7 +960,7 @@ static int uart_set_info(struct tty_struct *tty, struct tty_port *port,
> uport->fifosize = new_info->xmit_fifo_size;
>
> check_and_exit:
> - retval = 0;
> + retval = retval < 0 ? retval : 0;

Please no, do not use ? : unless you have to. Spell it out and use a
real if statement.

thanks,

greg k-h

2021-12-08 14:12:18

by Vihas Makwana

Subject: Re: [PATCH] tty: serial: return appropriate error on failure

>> Please no, do not use ? : unless you have to. Spell it out and use a
>> real if statement.

Okay. But I don't think it's required anymore, as Jiri pointed out in
https://bugzilla.kernel.org/show_bug.cgi?id=215205#c1

On Wed, Dec 8, 2021 at 11:15 AM Greg KH <[email protected]> wrote:
>
> On Wed, Dec 08, 2021 at 03:47:41AM +0530, Vihas Mak wrote:
> > when a user with CAP_SYS_ADMIN disabled calls ioctl (TIOCSSERIAL),
> > uart_set_info() returns 0 instead of -EPERM and the user remains unware
> > about what went wrong. Fix this.
> >
> > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=215205
> >
> > Signed-off-by: Vihas Mak <[email protected]>
> > ---
> > drivers/tty/serial/serial_core.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
> > index 61e3dd022..c204bdecc 100644
> > --- a/drivers/tty/serial/serial_core.c
> > +++ b/drivers/tty/serial/serial_core.c
> > @@ -960,7 +960,7 @@ static int uart_set_info(struct tty_struct *tty, struct tty_port *port,
> > uport->fifosize = new_info->xmit_fifo_size;
> >
> > check_and_exit:
> > - retval = 0;
> > + retval = retval < 0 ? retval : 0;
>
> Please no, do not use ? : unless you have to. Spell it out and use a
> real if statement.
>
> thanks,
>
> greg k-h



--
Thanks,
Vihas