ROMFS: romfs_lookup() shouldn't be doing a partial name comparison
romfs_lookup() should be using a routine akin to strcmp() on the backing store,
rather than one akin to strncmp(). If it uses the latter, it's liable to match
/bin/shutdown when looking up /bin/sh.
Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: Michal Simek <monstr@monstr.eu> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>