| Message ID | Zr5L8TUzkJcB9HcF@google.com |
|---|---|
| State | Accepted |
| Commit | 6994d8b84bfd71431bfccb5baf84a827086d48a5 |
| Headers | show |
| Series | Input: evdev - limit amount of data for writes | expand |
On Thu, Aug 15, 2024 at 11:41:53AM -0700, Dmitry Torokhov wrote: > Limit amount of data that can be written into an evdev instance at > a given time to 4096 bytes (170 input events) to avoid holding > evdev->mutex for too long and starving other users. > > Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> I'd expect anything coming near 170 input events is going to trigger SYN_DROPPED anyway, so: Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net> thanks. Cheers, Peter > --- > drivers/input/evdev.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c > index a8ce3d140722..eb4906552ac8 100644 > --- a/drivers/input/evdev.c > +++ b/drivers/input/evdev.c > @@ -498,6 +498,13 @@ static ssize_t evdev_write(struct file *file, const char __user *buffer, > struct input_event event; > int retval = 0; > > + /* > + * Limit amount of data we inject into the input subsystem so that > + * we do not hold evdev->mutex for too long. 4096 bytes corresponds > + * to 170 input events. > + */ > + count = min(count, 4096); > + > if (count != 0 && count < input_event_size()) > return -EINVAL; > > -- > 2.46.0.184.g6999bdac58-goog > > > -- > Dmitry
On Fri, Aug 16, 2024 at 10:18:05AM +1000, Peter Hutterer wrote: > On Thu, Aug 15, 2024 at 11:41:53AM -0700, Dmitry Torokhov wrote: > > Limit amount of data that can be written into an evdev instance at > > a given time to 4096 bytes (170 input events) to avoid holding > > evdev->mutex for too long and starving other users. > > > > Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> > > I'd expect anything coming near 170 input events is going to trigger > SYN_DROPPED anyway, so: This actually going the other direction (userspace -> kernel) so there will be no SYN_DROPPED, at least on the way in. > > Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net> Thanks for the review!
Hi Dmitry, On Thu, Aug 15, 2024 at 11:41:53AM -0700, Dmitry Torokhov wrote: > Limit amount of data that can be written into an evdev instance at > a given time to 4096 bytes (170 input events) to avoid holding > evdev->mutex for too long and starving other users. > > Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> Reviewed-by: Jeff LaBundy <jeff@labundy.com> > --- > drivers/input/evdev.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c > index a8ce3d140722..eb4906552ac8 100644 > --- a/drivers/input/evdev.c > +++ b/drivers/input/evdev.c > @@ -498,6 +498,13 @@ static ssize_t evdev_write(struct file *file, const char __user *buffer, > struct input_event event; > int retval = 0; > > + /* > + * Limit amount of data we inject into the input subsystem so that > + * we do not hold evdev->mutex for too long. 4096 bytes corresponds > + * to 170 input events. > + */ > + count = min(count, 4096); > + > if (count != 0 && count < input_event_size()) > return -EINVAL; > > -- > 2.46.0.184.g6999bdac58-goog > > > -- > Dmitry Kind regards, Jeff LaBundy
diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c index a8ce3d140722..eb4906552ac8 100644 --- a/drivers/input/evdev.c +++ b/drivers/input/evdev.c @@ -498,6 +498,13 @@ static ssize_t evdev_write(struct file *file, const char __user *buffer, struct input_event event; int retval = 0; + /* + * Limit amount of data we inject into the input subsystem so that + * we do not hold evdev->mutex for too long. 4096 bytes corresponds + * to 170 input events. + */ + count = min(count, 4096); + if (count != 0 && count < input_event_size()) return -EINVAL;
Limit amount of data that can be written into an evdev instance at a given time to 4096 bytes (170 input events) to avoid holding evdev->mutex for too long and starving other users. Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> --- drivers/input/evdev.c | 7 +++++++ 1 file changed, 7 insertions(+)