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Input: paper over a bug in Synaptics X driver 

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
This commit is contained in:
Dmitry Torokhov 2008-08-08 11:46:53 -04:00
parent 5402a7349d
commit f2afa7711f
1 changed files with 20 additions and 1 deletions
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21
drivers/input/evdev.c
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@ -647,8 +647,10 @@ 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;
@ -665,9 +667,26 @@ static int handle_eviocgbit(struct input_dev *dev, unsigned int cmd, void __user
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)