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| author | Ernesto A. Fernández <ernesto.mnd.fernandez@gmail.com> | 2018-08-24 03:00:25 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-08-24 04:48:42 +0300 |
| commit | a7ec7a4193a2eb3b5341243fc0b621c1ac9e4ec4 (patch) | |
| tree | 191476f760fc603cca157aa80f51198d62916cd0 | |
| parent | 815f0ddb346c196018d4d8f8f55c12b83da1de3f (diff) | |
| download | linux-a7ec7a4193a2eb3b5341243fc0b621c1ac9e4ec4.tar.xz | |
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>
| -rw-r--r-- | fs/hfsplus/dir.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/fs/hfsplus/dir.c b/fs/hfsplus/dir.c index c5a70f83dbe7..f37662675c3a 100644 --- a/fs/hfsplus/dir.c +++ b/fs/hfsplus/dir.c @@ -77,13 +77,13 @@ again: cpu_to_be32(HFSP_HARDLINK_TYPE) && entry.file.user_info.fdCreator == cpu_to_be32(HFSP_HFSPLUS_CREATOR) && + HFSPLUS_SB(sb)->hidden_dir && (entry.file.create_date == HFSPLUS_I(HFSPLUS_SB(sb)->hidden_dir)-> create_date || entry.file.create_date == HFSPLUS_I(d_inode(sb->s_root))-> - create_date) && - HFSPLUS_SB(sb)->hidden_dir) { + create_date)) { struct qstr str; char name[32]; |