Commit dfcec251 authored Aug 22, 2015 by santosh.shilimkar@oracle.com Committed by David S. Miller Aug 25, 2015

RDS: make sure rds_send_drop_to properly takes the m_rs_lock

rds_send_drop_to() is used during socket tear down to find all the
messages on the socket and flush them . It can race with the
acking code unless it takes the m_rs_lock on each and every message.

This plugs a hole where we didn't take m_rs_lock on any message that
didn't have the RDS_MSG_ON_CONN set. Taking m_rs_lock avoids
double frees and other memory corruptions as the ack code trusts
the message m_rs pointer on a socket that had actually been freed.

We must take m_rs_lock to access m_rs. Because of lock nesting and
rs access, we also need to acquire rs_lock.

Reviewed-by: Ajaykumar Hotchandani <ajaykumar.hotchandani@oracle.com>
Signed-off-by: Santosh Shilimkar <ssantosh@kernel.org>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 1c3be624

net/rds/send.c

+15 −1

Original line number	Diff line number	Diff line
		@@ -778,8 +778,22 @@ void rds_send_drop_to(struct rds_sock rs, struct sockaddr_in dest)
		while (!list_empty(&list)) {
		rm = list_entry(list.next, struct rds_message, m_sock_item);
		list_del_init(&rm->m_sock_item);

		rds_message_wait(rm);

		/* just in case the code above skipped this message
		* because RDS_MSG_ON_CONN wasn't set, run it again here
		* taking m_rs_lock is the only thing that keeps us
		* from racing with ack processing.
		*/
		spin_lock_irqsave(&rm->m_rs_lock, flags);

		spin_lock(&rs->rs_lock);
		__rds_send_complete(rs, rm, RDS_RDMA_CANCELED);
		spin_unlock(&rs->rs_lock);

		rm->m_rs = NULL;
		spin_unlock_irqrestore(&rm->m_rs_lock, flags);

		rds_message_put(rm);
		}
		}