0013-tty-n_r3964-properly-protect-sig_flags-of-client-str.patch

From 7105eeab4aa73032fe40f5e72f51601da0cd7c4f Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: Fri, 25 Jan 2019 16:35:57 +0100
Subject: [PATCH 13/15] tty: n_r3964: properly protect sig_flags of client
 structure

This cleans up the remaining users of the sig_flags field in the client
structure to allways access it under the client structure's lock.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/tty/n_r3964.c |   20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

--- a/drivers/tty/n_r3964.c
+++ b/drivers/tty/n_r3964.c
@@ -193,7 +193,6 @@ static void transmit_block(struct r3964_
 static void receive_char(struct r3964_info *pInfo, const unsigned char c);
 static void receive_error(struct r3964_info *pInfo, const char flag);
 static void on_timeout(struct timer_list *t);
-static int enable_signals(struct r3964_info *pInfo, struct pid *pid, int arg);
 static void add_msg(struct r3964_client_info *pClient, int msg_id, int arg,
 		int error_code, struct rx_block_header *pBlock);
 static struct r3964_message *remove_msg(struct r3964_client_info *client);
@@ -548,7 +547,14 @@ static void on_receive_block(struct r396
 	/* notify attached client processes: */
 	spin_lock_irqsave(&pInfo->lock, flags);
 	list_for_each_entry(pClient, &pInfo->clients, node) {
-		if (pClient->sig_flags & R3964_SIG_DATA) {
+		unsigned long client_flags;
+		unsigned int sig_flags;
+
+		spin_lock_irqsave(&pClient->lock, client_flags);
+		sig_flags = pClient->sig_flags;
+		spin_unlock_irqrestore(&pClient->lock, client_flags);
+
+		if (sig_flags & R3964_SIG_DATA) {
 			add_msg(pClient, R3964_MSG_DATA, length, R3964_OK,
 				pBlock);
 		}
@@ -799,8 +805,12 @@ static int enable_signals(struct r3964_i
 	} else {
 		pClient = findClient(pInfo, pid);
 		if (pClient) {
+			unsigned long client_flags;
+
 			/* update signal options */
+			spin_lock_irqsave(&pClient->lock, client_flags);
 			pClient->sig_flags = arg;
+			spin_unlock_irqrestore(&pClient->lock, client_flags);
 		} else {
 			/* add client to client list */
 			pClient = kmalloc(sizeof(struct r3964_client_info),
@@ -915,6 +925,7 @@ static void add_msg(struct r3964_client_
 {
 	struct r3964_message *pMsg;
 	unsigned long flags;
+	unsigned int sig_flags;
 
 	spin_lock_irqsave(&pClient->lock, flags);
 
@@ -935,12 +946,13 @@ static void add_msg(struct r3964_client_
 			TRACE_PE("add_msg - queue OVERFLOW-msg");
 		}
 	}
+
+	sig_flags = pClient->sig_flags;
 	spin_unlock_irqrestore(&pClient->lock, flags);
 
 	/* Send SIGIO signal to client process: */
-	if (pClient->sig_flags & R3964_USE_SIGIO) {
+	if (sig_flags & R3964_USE_SIGIO)
 		kill_pid(pClient->pid, SIGIO, 1);
-	}
 }
 
 static struct r3964_message *remove_msg(struct r3964_client_info *client)