Integer overflow in the agp_generic_insert_memory function in drivers/char/agp/generic.c in the Linux kernel before 2.6.38.5 allows local users to gain privileges or cause a denial of service (system crash) via a crafted AGPIOC_BIND agp_ioctl ioctl call.
Integer Overflow or Wraparound The product performs a calculation that can
produce an integer overflow or wraparound when the logic
assumes that the resulting value will always be larger than
the original value. This occurs when an integer value is
incremented to a value that is too large to store in the
associated representation. When this occurs, the value may
become a very small or negative number.