isofs: Fix infinite looping over CE entries

Rock Ridge extensions define so called Continuation Entries (CE)
which define where is further space with Rock Ridge data. Corrupted
isofs image can contain arbitrarily long chain of these, including a
one containing loop and thus causing kernel to end in an infinite loop
when traversing these entries. Limit the traversal to 32 entries which
should be more than enough space to store all the Rock Ridge data.

Change-Id: Ic0dc9a598245d4f10f9b83ade71ff412d37ac886
Reported-by: P J P <ppandit@redhat.com>
CC: stable@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
Git-commit: f54e18f1b831c92f6512d2eedb224cd63d607d3d
Git-repo: https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git


Signed-off-by: Shreyas Narayan <shrena@codeaurora.org>