1 files changed, 43 insertions, 20 deletions

diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c
index 2d65411f6763..a92d81567559 100644
--- a/drivers/input/evdev.c
+++ b/drivers/input/evdev.c
@@ -647,6 +647,47 @@ static int str_to_user(const char *str, unsigned int maxlen, void __user *p)
         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;
+
+        switch (_IOC_NR(cmd) & EV_MAX) {
+
+        case      0: bits = dev->evbit;  len = EV_MAX;  break;
+        case EV_KEY: bits = dev->keybit; len = KEY_MAX; break;
+        case EV_REL: bits = dev->relbit; len = REL_MAX; break;
+        case EV_ABS: bits = dev->absbit; len = ABS_MAX; break;
+        case EV_MSC: bits = dev->mscbit; len = MSC_MAX; break;
+        case EV_LED: bits = dev->ledbit; len = LED_MAX; break;
+        case EV_SND: bits = dev->sndbit; len = SND_MAX; break;
+        case EV_FF:  bits = dev->ffbit;  len = FF_MAX;  break;
+        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)
 {
@@ -733,26 +774,8 @@ static long evdev_do_ioctl(struct file *file, unsigned int cmd,
 
                 if (_IOC_DIR(cmd) == _IOC_READ) {
 
-                        if ((_IOC_NR(cmd) & ~EV_MAX) == _IOC_NR(EVIOCGBIT(0, 0))) {
-
-                                unsigned long *bits;
-                                int len;
-
-                                switch (_IOC_NR(cmd) & EV_MAX) {
-
-                                case      0: bits = dev->evbit;  len = EV_MAX;  break;
-                                case EV_KEY: bits = dev->keybit; len = KEY_MAX; break;
-                                case EV_REL: bits = dev->relbit; len = REL_MAX; break;
-                                case EV_ABS: bits = dev->absbit; len = ABS_MAX; break;
-                                case EV_MSC: bits = dev->mscbit; len = MSC_MAX; break;
-                                case EV_LED: bits = dev->ledbit; len = LED_MAX; break;
-                                case EV_SND: bits = dev->sndbit; len = SND_MAX; break;
-                                case EV_FF:  bits = dev->ffbit;  len = FF_MAX;  break;
-                                case EV_SW:  bits = dev->swbit;  len = SW_MAX;  break;
-                                default: return -EINVAL;
-                                }
-                                return bits_to_user(bits, len, _IOC_SIZE(cmd), p, compat_mode);
-                        }
+                        if ((_IOC_NR(cmd) & ~EV_MAX) == _IOC_NR(EVIOCGBIT(0, 0)))
+                                return handle_eviocgbit(dev, cmd, p, compat_mode);
 
                         if (_IOC_NR(cmd) == _IOC_NR(EVIOCGKEY(0)))
                                 return bits_to_user(dev->key, KEY_MAX, _IOC_SIZE(cmd),