ksmbd: limits exceeding the maximum allowable outstanding requests

mainline inclusion
from mainline-5.17-rc1
commit b589f5db
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I60T7G
CVE: NA

Reference: https://git.kernel.org/torvalds/linux/c/b589f5db6d4a

-------------------------------

If the client ignores the CreditResponse received from the server and
continues to send the request, ksmbd limits the requests if it exceeds
smb2 max credits.
Signed-off-by: NNamjae Jeon <linkinjeon@kernel.org>
Signed-off-by: NSteve French <stfrench@microsoft.com>
Signed-off-by: NJason Yan <yanaijie@huawei.com>
Signed-off-by: NZhong Jinghua <zhongjinghua@huawei.com>

fs/ksmbd/connection.c

@@ -63,6 +63,7 @@ struct ksmbd_conn *ksmbd_conn_alloc(void)
 	atomic_set(&conn->req_running, 0);
 	atomic_set(&conn->r_count, 0);
 	conn->total_credits = 1;
+	conn->outstanding_credits = 1;
 
 	init_waitqueue_head(&conn->req_running_q);
 	init_waitqueue_head(&conn->r_count_q);

fs/ksmbd/connection.h

@@ -54,7 +54,8 @@ struct ksmbd_conn {
 	atomic_t			req_running;
 	/* References which are made for this Server object*/
 	atomic_t			r_count;
-	unsigned short			total_credits;
+	unsigned int			total_credits;
+	unsigned int			outstanding_credits;
 	spinlock_t			credits_lock;
 	wait_queue_head_t		req_running_q;
 	wait_queue_head_t		r_count_q;

fs/ksmbd/smb2misc.c

@@ -333,7 +333,16 @@ static int smb2_validate_credit_charge(struct ksmbd_conn *conn,
 			    credit_charge, conn->total_credits);
 		ret = 1;
 	}
+
+	if ((u64)conn->outstanding_credits + credit_charge > conn->vals->max_credits) {
+		ksmbd_debug(SMB, "Limits exceeding the maximum allowable outstanding requests, given : %u, pending : %u\n",
+			    credit_charge, conn->outstanding_credits);
+		ret = 1;
+	} else
+		conn->outstanding_credits += credit_charge;
+
 	spin_unlock(&conn->credits_lock);
+
 	return ret;
 }
 

fs/ksmbd/smb2pdu.c

@@ -323,6 +323,7 @@ int smb2_set_rsp_credits(struct ksmbd_work *work)
 	}
 
 	conn->total_credits -= credit_charge;
+	conn->outstanding_credits -= credit_charge;
 	credits_requested = max_t(unsigned short,
 				  le16_to_cpu(req_hdr->CreditRequest), 1);