jdarith.c: Require cinfo->Se == DCTSIZE2 - 1
This fixes an oversight from the integration of the arithmetic entropy
codec from libjpeg (66f97e6820e2cc9ef7429ea36285c80ffda87c8f). I chose
to integrate the latest implementation available at the time, which was
from jpeg-8b. However, I naively replaced cinfo->lim_Se with
DCTSIZE2 - 1, not realizing that-- because of SmartScale-- jpeg-8b
contains additional code
(https://github.com/libjpeg-turbo/libjpeg-turbo/blob/jpeg-8b/jdinput.c#L249-L334)
that guards against illegal values of cinfo->Se >= DCTSIZE2. Thus,
libjpeg-turbo's implementation of arithmetic decoding has never guarded
against such illegal values. This commit restores the relevant check
from the original jpeg-6b arithmetic entropy codec patch ("jpeg-ari",
1e247ac854f8e33682bcfea475f6bccc42377208).
Fixes #564
1 file changed
