Commit 18b4fac5 authored by Namjae Jeon's avatar Namjae Jeon Committed by Steve French
Browse files

ksmbd: fix use-after-free in smb_break_all_levII_oplock() 



There is a room in smb_break_all_levII_oplock that can cause racy issues
when unlocking in the middle of the loop. This patch use read lock
to protect whole loop.

Cc: stable@vger.kernel.org
Reported-by: default avatarNorbert Szetei <norbert@doyensec.com>
Tested-by: default avatarNorbert Szetei <norbert@doyensec.com>
Signed-off-by: default avatarNamjae Jeon <linkinjeon@kernel.org>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
parent 21a4e475

fs/smb/server/oplock.c

+9 −20
Original line number Diff line number Diff line
@@ -129,14 +129,6 @@ static void free_opinfo(struct oplock_info *opinfo) 
	kfree(opinfo);

}



static inline void opinfo_free_rcu(struct rcu_head *rcu_head)

{

	struct oplock_info *opinfo;



	opinfo = container_of(rcu_head, struct oplock_info, rcu_head);

	free_opinfo(opinfo);

}



struct oplock_info *opinfo_get(struct ksmbd_file *fp)

{

	struct oplock_info *opinfo;
@@ -157,8 +149,8 @@ static struct oplock_info *opinfo_get_list(struct ksmbd_inode *ci) 
	if (list_empty(&ci->m_op_list))

		return NULL;



	rcu_read_lock();

	opinfo = list_first_or_null_rcu(&ci->m_op_list, struct oplock_info,

	down_read(&ci->m_lock);

	opinfo = list_first_entry(&ci->m_op_list, struct oplock_info,

					op_entry);

	if (opinfo) {

		if (opinfo->conn == NULL ||
@@ -171,8 +163,7 @@ static struct oplock_info *opinfo_get_list(struct ksmbd_inode *ci) 
			}

		}

	}



	rcu_read_unlock();

	up_read(&ci->m_lock);



	return opinfo;

}
@@ -185,7 +176,7 @@ void opinfo_put(struct oplock_info *opinfo) 
	if (!atomic_dec_and_test(&opinfo->refcount))

		return;



	call_rcu(&opinfo->rcu_head, opinfo_free_rcu);

	free_opinfo(opinfo);

}



static void opinfo_add(struct oplock_info *opinfo)
@@ -193,7 +184,7 @@ static void opinfo_add(struct oplock_info *opinfo) 
	struct ksmbd_inode *ci = opinfo->o_fp->f_ci;



	down_write(&ci->m_lock);

	list_add_rcu(&opinfo->op_entry, &ci->m_op_list);

	list_add(&opinfo->op_entry, &ci->m_op_list);

	up_write(&ci->m_lock);

}
@@ -207,7 +198,7 @@ static void opinfo_del(struct oplock_info *opinfo) 
		write_unlock(&lease_list_lock);

	}

	down_write(&ci->m_lock);

	list_del_rcu(&opinfo->op_entry);

	list_del(&opinfo->op_entry);

	up_write(&ci->m_lock);

}
@@ -1347,8 +1338,8 @@ void smb_break_all_levII_oplock(struct ksmbd_work *work, struct ksmbd_file *fp, 
	ci = fp->f_ci;

	op = opinfo_get(fp);



	rcu_read_lock();

	list_for_each_entry_rcu(brk_op, &ci->m_op_list, op_entry) {

	down_read(&ci->m_lock);

	list_for_each_entry(brk_op, &ci->m_op_list, op_entry) {

		if (brk_op->conn == NULL)

			continue;
@@ -1358,7 +1349,6 @@ void smb_break_all_levII_oplock(struct ksmbd_work *work, struct ksmbd_file *fp, 
		if (ksmbd_conn_releasing(brk_op->conn))

			continue;



		rcu_read_unlock();

		if (brk_op->is_lease && (brk_op->o_lease->state &

		    (~(SMB2_LEASE_READ_CACHING_LE |

				SMB2_LEASE_HANDLE_CACHING_LE)))) {
@@ -1388,9 +1378,8 @@ void smb_break_all_levII_oplock(struct ksmbd_work *work, struct ksmbd_file *fp, 
		oplock_break(brk_op, SMB2_OPLOCK_LEVEL_NONE, NULL);

next:

		opinfo_put(brk_op);

		rcu_read_lock();

	}

	rcu_read_unlock();

	up_read(&ci->m_lock);



	if (op)

		opinfo_put(op);

fs/smb/server/oplock.h

+0 −1
Original line number Diff line number Diff line
@@ -71,7 +71,6 @@ struct oplock_info { 
	struct list_head        lease_entry;

	wait_queue_head_t oplock_q; /* Other server threads */

	wait_queue_head_t oplock_brk; /* oplock breaking wait */

	struct rcu_head		rcu_head;

};



struct lease_break_info {