diff options
| author | Chen Zhongjin <chenzhongjin@huawei.com> | 2022-11-28 11:33:05 +0100 |
|---|---|---|
| committer | Miklos Szeredi <mszeredi@redhat.com> | 2022-11-28 11:33:05 +0100 |
| commit | 672e4268b2863d7e4978dfed29552b31c2f9bd4e (patch) | |
| tree | 68402976a308f4f3632a8b4ed2e9639b50812ad7 | |
| parent | eb7081409f94a9a8608593d0fb63a1aa3d6f95d8 (diff) | |
ovl: fix use inode directly in rcu-walk mode
ovl_dentry_revalidate_common() can be called in rcu-walk mode. As document
said, "in rcu-walk mode, d_parent and d_inode should not be used without
care".
Check inode here to protect access under rcu-walk mode.
Fixes: bccece1ead36 ("ovl: allow remote upper")
Reported-and-tested-by: syzbot+a4055c78774bbf3498bb@syzkaller.appspotmail.com
Signed-off-by: Chen Zhongjin <chenzhongjin@huawei.com>
Cc: <stable@vger.kernel.org> # v5.7
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
| -rw-r--r-- | fs/overlayfs/super.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index a29a8afe9b26..3d14a3f1465d 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -139,11 +139,16 @@ static int ovl_dentry_revalidate_common(struct dentry *dentry, unsigned int flags, bool weak) { struct ovl_entry *oe = dentry->d_fsdata; + struct inode *inode = d_inode_rcu(dentry); struct dentry *upper; unsigned int i; int ret = 1; - upper = ovl_dentry_upper(dentry); + /* Careful in RCU mode */ + if (!inode) + return -ECHILD; + + upper = ovl_i_dentry_upper(inode); if (upper) ret = ovl_revalidate_real(upper, flags, weak); |