kernel/groups.c: fix integer overflow in groups_search

kernel/groups.c: fix integer overflow in groups_search

commit 1c24de60e50fb19b94d94225458da17c720f0729 upstream.

gid_t is a unsigned int.  If group_info contains a gid greater than
MAX_INT, groups_search() function may look on the wrong side of the search
tree.

This solves some unfair "permission denied" problems.

Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>