hfsplus: fix NULL dereference in hfsplus_lookup()
An HFS+ filesystem can be mounted read-only without having a metadata
directory, which is needed to support hardlinks. But if the catalog
data is corrupted, a directory lookup may still find dentries claiming
to be hardlinks.
hfsplus_lookup() does check that ->hidden_dir is not NULL in such a
situation, but mistakenly does so after dereferencing it for the first
time. Reorder this check to prevent a crash.
This happens when looking up corrupted catalog data (dentry) on a
filesystem with no metadata directory (this could only ever happen on a
read-only mount). Wen Xu sent the replication steps in detail to the
fsdevel list: https://bugzilla.kernel.org/show_bug.cgi?id=200297
Link: http://lkml.kernel.org/r/20180712215344.q44dyrhymm4ajkao@eaf
Signed-off-by: Ernesto A. Fernández <[email protected]>
Reported-by: Wen Xu <[email protected]>
Cc: Viacheslav Dubeyko <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
1 file changed
