diff options
| author | Xiubo Li | 2022-11-17 10:57:53 +0800 |
|---|---|---|
| committer | Ilya Dryomov | 2023-01-02 12:27:25 +0100 |
| commit | 8e1858710d9a71d88acd922f2e95d1eddb90eea0 (patch) | |
| tree | 478a0dfc7713b89e895ea5ac7e8ed5020b782107 /fs | |
| parent | 461ab10ef7e6ea9b41a0571a7fc6a72af9549a3c (diff) | |
ceph: avoid use-after-free in ceph_fl_release_lock()
When ceph releasing the file_lock it will try to get the inode pointer
from the fl->fl_file, which the memory could already be released by
another thread in filp_close(). Because in VFS layer the fl->fl_file
doesn't increase the file's reference counter.
Will switch to use ceph dedicate lock info to track the inode.
And in ceph_fl_release_lock() we should skip all the operations if the
fl->fl_u.ceph.inode is not set, which should come from the request
file_lock. And we will set fl->fl_u.ceph.inode when inserting it to the
inode lock list, which is when copying the lock.
Link: https://tracker.ceph.com/issues/57986
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/ceph/locks.c | 20 |
1 files changed, 18 insertions, 2 deletions
diff --git a/fs/ceph/locks.c b/fs/ceph/locks.c index 6b3b8c299c17..9c8dc8a55e7e 100644 --- a/fs/ceph/locks.c +++ b/fs/ceph/locks.c @@ -34,18 +34,34 @@ static void ceph_fl_copy_lock(struct file_lock *dst, struct file_lock *src) { struct inode *inode = file_inode(dst->fl_file); atomic_inc(&ceph_inode(inode)->i_filelock_ref); + dst->fl_u.ceph.inode = igrab(inode); } +/* + * Do not use the 'fl->fl_file' in release function, which + * is possibly already released by another thread. + */ static void ceph_fl_release_lock(struct file_lock *fl) { - struct inode *inode = file_inode(fl->fl_file); - struct ceph_inode_info *ci = ceph_inode(inode); + struct inode *inode = fl->fl_u.ceph.inode; + struct ceph_inode_info *ci; + + /* + * If inode is NULL it should be a request file_lock, + * nothing we can do. + */ + if (!inode) + return; + + ci = ceph_inode(inode); if (atomic_dec_and_test(&ci->i_filelock_ref)) { /* clear error when all locks are released */ spin_lock(&ci->i_ceph_lock); ci->i_ceph_flags &= ~CEPH_I_ERROR_FILELOCK; spin_unlock(&ci->i_ceph_lock); } + fl->fl_u.ceph.inode = NULL; + iput(inode); } static const struct file_lock_operations ceph_fl_lock_ops = { |