From 68e787c3c80059c776d1d7afb20f5eb9f20237a5 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ernesto=20A=2E=20Fern=C3=A1ndez?= Date: Thu, 23 Aug 2018 17:00:25 -0700 Subject: [PATCH] hfsplus: fix NULL dereference in hfsplus_lookup() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit [ Upstream commit a7ec7a4193a2eb3b5341243fc0b621c1ac9e4ec4 ] 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 CVE: CVE-2018-14617 Upstream-Status: Backport Link: http://lkml.kernel.org/r/20180712215344.q44dyrhymm4ajkao@eaf Signed-off-by: Ernesto A. Fernández Reported-by: Wen Xu Cc: Viacheslav Dubeyko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sona Sarmadi --- fs/hfsplus/dir.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/hfsplus/dir.c b/fs/hfsplus/dir.c index e8120a2..1a44c46 100644 --- a/fs/hfsplus/dir.c +++ b/fs/hfsplus/dir.c @@ -78,13 +78,13 @@ static struct dentry *hfsplus_lookup(struct inode *dir, struct dentry *dentry, 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]; -- 1.9.1