From 439581ec07fa9cf3f519dd461a2cf41cfd3adcb4 Mon Sep 17 00:00:00 2001
From: Peter Korsgaard <jacmet@sunsite.dk>
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 <baruch@tkos.co.il>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>
Acked-by: Henrik Rydberg <rydberg@euromail.se>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
---
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 c8471a2552e7..7f42d3a454d2 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);
--
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