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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 09:00:16 +0000 (11:00 +0200)
commit04affe4e117169e75c4ff1f12dd30d74c9a629fc
tree7f44c2a51a6c9ba4e8332a67d9a46e4a9f43e3ce
parent7498bd6058405ba17df33be06046fefdb419fe00
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