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ceph: avoid use-after-free in ceph_fl_release_lock()

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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>
This commit is contained in:
Xiubo Li 2022-11-17 10:57:53 +08:00 committed by Ilya Dryomov
parent 461ab10ef7
commit 8e1858710d
2 changed files with 21 additions and 2 deletions
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20
fs/ceph/locks.c
View File

@ -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 = {

3
include/linux/fs.h
View File

@ -1119,6 +1119,9 @@ struct file_lock {
int state; /* state of grant or error if -ve */
unsigned int debug_id;
} afs;
struct {
struct inode *inode;
} ceph;
} fl_u;
} __randomize_layout;