libsepol: ebitmap: reject loading bitmaps with incorrect high bit
Currently ebitmap_load() accepts loading a bitmap with highbit=192 and
one node {startbit=0, map=0x2}. When iterating over the bitmap,
ebitmap_for_each_bit() is expected to only yield "1" but it gives the
following bits: 1, 65, 129.
This is due to two facts in ebitmap_for_each_bit() implementation:
* ebitmap_next() stays on the first (and only) node of the bitmap
instead of stopping the iteration.
* the end condition of the for loop consists in comparing the bit with
ebitmap_length() (ie. the bitmap highbit), which is above the limit of
the last node here.
These are not bugs when the bitmap highbit is equals to
l->startbit+MAPSIZE, where l is the last node (this is how
ebitmap_set_bit() sets it). So a simple fix consists in making
ebitmap_load() reject bitmaps which are loaded with an invalid highbit
value.
This issue has been found while fuzzing semodule_package with the
American Fuzzy Lop.
Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org>
1 file changed