firewire: cdev: fix 32 bit userland on 64 bit kernel compat corner cases
authorStefan Richter <stefanr@s5r6.in-berlin.de>
Wed, 10 Aug 2011 22:06:04 +0000 (00:06 +0200)
committerStefan Richter <stefanr@s5r6.in-berlin.de>
Fri, 12 Aug 2011 13:30:08 +0000 (15:30 +0200)
commit9c1176b6a28850703ea6e3a0f0c703f6d6c61cd3
tree5e51f0e7e36c78ae63e3128125cb008bcc442aa0
parent9a00c24ae7cb08dcd46edf1327a47871e8466444
firewire: cdev: fix 32 bit userland on 64 bit kernel compat corner cases

Clemens points out that we need to use compat_ptr() in order to safely
cast from u64 to addresses of a 32-bit usermode client.

Before, our conversion went wrong
  - in practice if the client cast from pointer to integer such that
    sign-extension happened, (libraw1394 and libdc1394 at least were not
    doing that, IOW were not affected)
or
  - in theory on s390 (which doesn't have FireWire though) and on the
    tile architecture, regardless of what the client does.
The bug would usually be observed as the initial get_info ioctl failing
with "Bad address" (EFAULT).

Reported-by: Carl Karsten <carl@personnelware.com>
Reported-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
drivers/firewire/core-cdev.c