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authorErnesto A. Fernández <ernesto.mnd.fernandez@gmail.com>2018-08-23 17:00:25 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-08-23 18:48:42 -0700
commita7ec7a4193a2eb3b5341243fc0b621c1ac9e4ec4 (patch)
tree191476f760fc603cca157aa80f51198d62916cd0 /fs
parent815f0ddb346c196018d4d8f8f55c12b83da1de3f (diff)
download96b-common-a7ec7a4193a2eb3b5341243fc0b621c1ac9e4ec4.tar.gz
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>
Diffstat (limited to 'fs')
-rw-r--r--fs/hfsplus/dir.c4
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];