media: v4l2-compat-ioctl32: Fix timespec conversion
authorDaniel Mentz <danielmentz@google.com>
Thu, 3 Aug 2017 03:42:17 +0000 (23:42 -0400)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 27 Sep 2017 12:39:24 +0000 (14:39 +0200)
commit7717a7378c53a510872db75d65879dc8eaca24b5
tree0b34cb1d6c9c2223976bb581f79d2c9140bce77e
parentde4360dd3519629fc0aabe6e87843038b84d75e3
media: v4l2-compat-ioctl32: Fix timespec conversion

commit 9c7ba1d7634cef490b85bc64c4091ff004821bfd upstream.

Certain syscalls like recvmmsg support 64 bit timespec values for the
X32 ABI. The helper function compat_put_timespec converts a timespec
value to a 32 bit or 64 bit value depending on what ABI is used. The
v4l2 compat layer, however, is not designed to support 64 bit timespec
values and always uses 32 bit values. Hence, compat_put_timespec must
not be used.

Without this patch, user space will be provided with bad timestamp
values from the VIDIOC_DQEVENT ioctl. Also, fields of the struct
v4l2_event32 that come immediately after timestamp get overwritten,
namely the field named id.

Fixes: 81993e81a994 ("compat: Get rid of (get|put)_compat_time(val|spec)")
Cc: H. Peter Anvin <hpa@linux.intel.com>
Cc: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Cc: Tiffany Lin <tiffany.lin@mediatek.com>
Cc: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Cc: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Daniel Mentz <danielmentz@google.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/media/v4l2-core/v4l2-compat-ioctl32.c