]> git.proxmox.com Git - mirror_ubuntu-eoan-kernel.git/commit
hfsplus: fix NULL dereference in hfsplus_lookup()
authorErnesto A. Fernández <ernesto.mnd.fernandez@gmail.com>
Fri, 24 Aug 2018 00:00:25 +0000 (17:00 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 24 Aug 2018 01:48:42 +0000 (18:48 -0700)
commita7ec7a4193a2eb3b5341243fc0b621c1ac9e4ec4
tree191476f760fc603cca157aa80f51198d62916cd0
parent815f0ddb346c196018d4d8f8f55c12b83da1de3f
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 <ernesto.mnd.fernandez@gmail.com>
Reported-by: Wen Xu <wen.xu@gatech.edu>
Cc: Viacheslav Dubeyko <slava@dubeyko.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fs/hfsplus/dir.c