Actually, disregard my thing about case - I was reading the -R as an effort to remove read permissions which makes no sense, but that was a recursive option. (One reason I like the numbers.)
chmod a+rx,u+rwx /usr/share/icons (I think?)
chmod 755 /usr/share/icons
You may want to do
chmod -R a+rx,u+rwx blah
chmod -R 755 blah
but that depends on what the permissions of the files in the directory are. How'd it get screwed up, anyway? AFAIK, those should be readable by default.