From 439581ec07fa9cf3f519dd461a2cf41cfd3adcb4 Mon Sep 17 00:00:00 2001 From: Peter Korsgaard Date: Fri, 25 Feb 2011 09:30:46 -0800 Subject: [PATCH] Input: evdev - fix evdev_write return value on partial writes As was recently brought up on the busybox list (http://lists.busybox.net/pipermail/busybox/2011-January/074565.html), evdev_write doesn't properly check the count argument, which will lead to a return value > count on partial writes if the remaining bytes are accessible - causing userspace confusion. Fix it by only handling each full input_event structure and return -EINVAL if less than 1 struct was written, similar to how it is done in evdev_read. Reported-by: Baruch Siach Signed-off-by: Peter Korsgaard Acked-by: Henrik Rydberg Signed-off-by: Dmitry Torokhov --- drivers/input/evdev.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c index c8471a2552e..7f42d3a454d 100644 --- a/drivers/input/evdev.c +++ b/drivers/input/evdev.c @@ -321,6 +321,9 @@ static ssize_t evdev_write(struct file *file, const char __user *buffer, struct input_event event; int retval; + if (count < input_event_size()) + return -EINVAL; + retval = mutex_lock_interruptible(&evdev->mutex); if (retval) return retval; @@ -330,17 +333,16 @@ static ssize_t evdev_write(struct file *file, const char __user *buffer, goto out; } - while (retval < count) { - + do { if (input_event_from_user(buffer + retval, &event)) { retval = -EFAULT; goto out; } + retval += input_event_size(); input_inject_event(&evdev->handle, event.type, event.code, event.value); - retval += input_event_size(); - } + } while (retval + input_event_size() <= count); out: mutex_unlock(&evdev->mutex); -- 2.20.1