keytable: Always check if strtok return value is null

The Mayhem Team found a crash caused by a nullptr.
Details are here:
http://www.forallsecure.com/bug-reports/567323cd26f180910beb03ae26afb40c432a0c6a/

Signed-off-by: Gregor Jasny <gjasny@googlemail.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Mauro Carvalho Chehab <mchehab@redhat.com>
(cherry picked from commit e0f869b3d16a05cd30899c7712813af75cbe2ffa)
libv4lconvert: Prevent integer overflow by checking width and height

The Mayhem Team found a crash caused by an integer overflow.
Details are here:
http://www.forallsecure.com/bug-reports/8aae67d864bce76993f3f9812b4a2aeea0eb38da/

Signed-off-by: Gregor Jasny <gjasny@googlemail.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Mauro Carvalho Chehab <mchehab@redhat.com>
(cherry picked from commit 06d15f95ed47c6daf716d8f66eba05ecc5a82b4e)