syzbot is reporting NULL pointer dereference at reiserfs_security_init()
[1], for commit ab17c4f02156c4f7 ("reiserfs: fixup xattr_root caching") is
assuming that REISERFS_SB(s)->xattr_root != NULL in
reiserfs_xattr_jcreate_nblocks() despite that commit made
REISERFS_SB(sb)->priv_root != NULL && REISERFS_SB(s)->xattr_root == NULL
case possible.
I guess that commit 6cb4aff0a77cc0e6 ("reiserfs: fix oops while creating
privroot with selinux enabled") wanted to check xattr_root != NULL before
reiserfs_xattr_jcreate_nblocks(), for the changelog is talking about the
xattr root.
The issue is that while creating the privroot during mount
reiserfs_security_init calls reiserfs_xattr_jcreate_nblocks which
dereferences the xattr root. The xattr root doesn't exist, so we get an
oops.
Therefore, update reiserfs_xattrs_initialized() to check both the privroot
and the xattr root.
[1] https://syzkaller.appspot.com/bug?id=8abaedbdeb32c861dc5340544284167dd0e46cde
Reported-and-tested-by: syzbot <syzbot+690cb1e51970435f9775@xxxxxxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Fixes: 6cb4aff0a77cc0e6 ("reiserfs: fix oops while creating privroot with selinux enabled")
---
fs/reiserfs/xattr.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
Escalating from reiserfs-devel@xxxxxxxxxxxxxxx to linux-fsdevel@xxxxxxxxxxxxxxx , for
no response from reiserfs developers for one month. If still no response from fsdevel
people, I would have to directly send to Linus...
diff --git a/fs/reiserfs/xattr.h b/fs/reiserfs/xattr.h
index c764352447ba..81bec2c80b25 100644
--- a/fs/reiserfs/xattr.h
+++ b/fs/reiserfs/xattr.h
@@ -43,7 +43,7 @@ void reiserfs_security_free(struct reiserfs_security_handle *sec);
static inline int reiserfs_xattrs_initialized(struct super_block *sb)
{
- return REISERFS_SB(sb)->priv_root != NULL;
+ return REISERFS_SB(sb)->priv_root && REISERFS_SB(sb)->xattr_root;
}
#define xattr_size(size) ((size) + sizeof(struct reiserfs_xattr_header))
--
2.18.4
