* [PATCH] staging: fwserial: Fix potential NULL pointer dereferences
@ 2021-05-21 11:43 Evgeny Novikov
2021-05-21 11:52 ` Greg Kroah-Hartman
0 siblings, 1 reply; 3+ messages in thread
From: Evgeny Novikov @ 2021-05-21 11:43 UTC (permalink / raw)
To: Greg Kroah-Hartman
Cc: Evgeny Novikov, Johan Hovold, Nikolay Kyx, Dinghao Liu,
Abheek Dhawan, Lee Gibson, linux-staging, linux-kernel,
ldv-project
If fwtty_install() will be invoked with such tty->index that will be
not less than MAX_TOTAL_PORTS then fwtty_port_get() will return NULL and
fwtty_install() will either assign it to tty->driver_data or dereference
in fwtty_port_put() (if tty_standard_install() will fail). The similar
situation is with fwloop_install(). The patch fixes both cases.
Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Evgeny Novikov <novikov@ispras.ru>
---
drivers/staging/fwserial/fwserial.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/staging/fwserial/fwserial.c b/drivers/staging/fwserial/fwserial.c
index 1ee6382cafc4..d0810896511e 100644
--- a/drivers/staging/fwserial/fwserial.c
+++ b/drivers/staging/fwserial/fwserial.c
@@ -1069,6 +1069,9 @@ static int fwtty_install(struct tty_driver *driver, struct tty_struct *tty)
struct fwtty_port *port = fwtty_port_get(tty->index);
int err;
+ if (!port)
+ return -ENODEV;
+
err = tty_standard_install(driver, tty);
if (!err)
tty->driver_data = port;
@@ -1082,6 +1085,9 @@ static int fwloop_install(struct tty_driver *driver, struct tty_struct *tty)
struct fwtty_port *port = fwtty_port_get(table_idx(tty->index));
int err;
+ if (!port)
+ return -ENODEV;
+
err = tty_standard_install(driver, tty);
if (!err)
tty->driver_data = port;
--
2.26.2
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] staging: fwserial: Fix potential NULL pointer dereferences
2021-05-21 11:43 [PATCH] staging: fwserial: Fix potential NULL pointer dereferences Evgeny Novikov
@ 2021-05-21 11:52 ` Greg Kroah-Hartman
[not found] ` <219911622016850@mail.yandex.ru>
0 siblings, 1 reply; 3+ messages in thread
From: Greg Kroah-Hartman @ 2021-05-21 11:52 UTC (permalink / raw)
To: Evgeny Novikov
Cc: Johan Hovold, Nikolay Kyx, Dinghao Liu, Abheek Dhawan,
Lee Gibson, linux-staging, linux-kernel, ldv-project
On Fri, May 21, 2021 at 02:43:39PM +0300, Evgeny Novikov wrote:
> If fwtty_install() will be invoked with such tty->index that will be
> not less than MAX_TOTAL_PORTS then fwtty_port_get() will return NULL and
> fwtty_install() will either assign it to tty->driver_data or dereference
> in fwtty_port_put() (if tty_standard_install() will fail). The similar
> situation is with fwloop_install(). The patch fixes both cases.
But how can those cases ever happen?
> Found by Linux Driver Verification project (linuxtesting.org).
>
> Signed-off-by: Evgeny Novikov <novikov@ispras.ru>
> ---
> drivers/staging/fwserial/fwserial.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/staging/fwserial/fwserial.c b/drivers/staging/fwserial/fwserial.c
> index 1ee6382cafc4..d0810896511e 100644
> --- a/drivers/staging/fwserial/fwserial.c
> +++ b/drivers/staging/fwserial/fwserial.c
> @@ -1069,6 +1069,9 @@ static int fwtty_install(struct tty_driver *driver, struct tty_struct *tty)
> struct fwtty_port *port = fwtty_port_get(tty->index);
> int err;
>
> + if (!port)
> + return -ENODEV;
there's already a valid tty pointer here, so the index can not be "too
big".
> +
> err = tty_standard_install(driver, tty);
> if (!err)
> tty->driver_data = port;
> @@ -1082,6 +1085,9 @@ static int fwloop_install(struct tty_driver *driver, struct tty_struct *tty)
> struct fwtty_port *port = fwtty_port_get(table_idx(tty->index));
> int err;
>
> + if (!port)
> + return -ENODEV;
> +
Same here, how can this ever happen?
thanks,
greg k-h
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] staging: fwserial: Fix potential NULL pointer dereferences
[not found] ` <219911622016850@mail.yandex.ru>
@ 2021-05-26 8:45 ` Greg Kroah-Hartman
0 siblings, 0 replies; 3+ messages in thread
From: Greg Kroah-Hartman @ 2021-05-26 8:45 UTC (permalink / raw)
To: Evgeny Novikov
Cc: Johan Hovold, Nikolay Kyx, Dinghao Liu, Abheek Dhawan,
Lee Gibson, linux-staging, linux-kernel, ldv-project
On Wed, May 26, 2021 at 11:21:36AM +0300, Evgeny Novikov wrote:
> Now I see that we need to restrict in specifications those values that
> can be passed to the install callback of tty_operations according to
> a first actual argument of tty_alloc_driver(). Thank you for pointing
> this out.
I do not understand what you mean here at all, sorry.
What "specifications"?
confused,
greg k-h
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2021-05-26 8:45 UTC | newest]
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2021-05-21 11:43 [PATCH] staging: fwserial: Fix potential NULL pointer dereferences Evgeny Novikov
2021-05-21 11:52 ` Greg Kroah-Hartman
[not found] ` <219911622016850@mail.yandex.ru>
2021-05-26 8:45 ` Greg Kroah-Hartman
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