Re: [PATCH] Input: uinput - handle compat ioctl for UI_SET_PHYS

Hi Dmitry,

On Sat, May 21, 2016 at 12:32 AM, Dmitry Torokhov
[off-list ref] wrote:

Hi Ricky,

On Tue, May 17, 2016 at 11:39:45PM +0800, Ricky Liang wrote:

quoted

When running a 32-bit userspace on a 64-bit kernel, the UI_SET_PHYS
ioctl needs to be treated with special care, as it has the pointer
size encoded in the command.

Signed-off-by: Ricky Liang <redacted>
---
 drivers/input/misc/uinput.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/input/misc/uinput.c b/drivers/input/misc/uinput.c
index abe1a92..b4d1b1d 100644
--- a/drivers/input/misc/uinput.c
+++ b/drivers/input/misc/uinput.c

@@ -984,6 +984,15 @@ static long uinput_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 static long uinput_compat_ioctl(struct file *file,
                              unsigned int cmd, unsigned long arg)
 {
+     switch (_IOC_NR(cmd)) {
+             case _IOC_NR(UI_SET_PHYS):
+                     if (_IOC_SIZE(cmd) == sizeof(compat_uptr_t)) {
+                             cmd &= ~IOCSIZE_MASK;
+                             cmd |= sizeof(void *) << IOCSIZE_SHIFT;
+                     }
+                     break;
+     }
+

This looks quite complicated... Can we do this:

#define UI_SET_PHYS_COMPAT __IOW(UINPUT_IOCTL_BASE, 108, compat_uptr_t)

...

        if (cmd == UI_SET_PHYS_COMPAT)
                cmd = UI_SET_PHYS;

quoted

      return uinput_ioctl_handler(file, cmd, arg, compat_ptr(arg));
 }
 #endif

We can use the local define instead of manipulating cmd size because we
will never going to change UI_SET_PHYS definition, since it is part of
uapi.

Sounds good. I'll send v2 to implement this.

Thanks,
Ricky

Thanks.

--
Dmitry