only the else changes finfo so reset inside there. not really any bug
at all byt style-wise a bit better and analysers don't like it
found by PVS studio
gif's logical screen size (which is considered the image size)
might be different from the size of each frame.
when decoding a frame, the width and height of the decoded data should be
based on the size of the frame, not on the size of the logical screen size.
if a frame is decoded into a buffer of screen size, this might happen
(frame = 6 X 3, logical screen = 5 X 3)
OOOXXX OOOXX
OOOXXX => XOOOX
OOOXXX XXOOO
@fix
if gif has example 4 colors in colormap, pixels provided still can
hold values higher than 3 (4, 8, 255 etc.) ass a pixel is still a
byte. it should not, but it could. technically it'd be nice for gitlib
to pad its palette out to 256 entires to ensure this cant be a
problem, but it doesn't have to , so make a local copy of the cmap
when decoding pixels and pad out to 256 entires (using color 0 as any
value > pallette ize is invalid anyway so any color will do).
this fixes a possible security attack vector in reading memory out of
bounds of an allocated array. not very far out of bounds - but enough
to cause a crash - ie a dos attack, (not to inject code though).
@fix
Elyes HAOUAS
Carsten Haitzler
Cedric BAIL
Jaeun Choi
Cedric BAIL
Stefan Schmidt
Bogdan Devichev