Input: paper over a bug in Synaptics X driver
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c
index ef8c2ed..a92d815 100644
--- a/drivers/input/evdev.c
+++ b/drivers/input/evdev.c
@@ -647,8 +647,10 @@
return copy_to_user(p, str, len) ? -EFAULT : len;
}
+#define OLD_KEY_MAX 0x1ff
static int handle_eviocgbit(struct input_dev *dev, unsigned int cmd, void __user *p, int compat_mode)
{
+ static unsigned long keymax_warn_time;
unsigned long *bits;
int len;
@@ -665,9 +667,26 @@
case EV_SW: bits = dev->swbit; len = SW_MAX; break;
default: return -EINVAL;
}
+
+ /*
+ * Work around bugs in userspace programs that like to do
+ * EVIOCGBIT(EV_KEY, KEY_MAX) and not realize that 'len'
+ * should be in bytes, not in bits.
+ */
+ if ((_IOC_NR(cmd) & EV_MAX) == EV_KEY && _IOC_SIZE(cmd) == OLD_KEY_MAX) {
+ len = OLD_KEY_MAX;
+ if (printk_timed_ratelimit(&keymax_warn_time, 10 * 1000))
+ printk(KERN_WARNING
+ "evdev.c(EVIOCGBIT): Suspicious buffer size %d, "
+ "limiting output to %d bytes. See "
+ "http://userweb.kernel.org/~dtor/eviocgbit-bug.html\n",
+ OLD_KEY_MAX,
+ BITS_TO_LONGS(OLD_KEY_MAX) * sizeof(long));
+ }
+
return bits_to_user(bits, len, _IOC_SIZE(cmd), p, compat_mode);
}
-
+#undef OLD_KEY_MAX
static long evdev_do_ioctl(struct file *file, unsigned int cmd,
void __user *p, int compat_mode)