rose: fix use-after-free, dev_put leak, and timer race in rose module

include/hamradio_compat.h

@@ -2,6 +2,7 @@
 #ifndef _MOD_ORPHAN_COMPAT_H
 #define _MOD_ORPHAN_COMPAT_H
 
+#include <linux/version.h>
 #include <linux/slab.h>
 #include <linux/overflow.h>
 
@@ -35,4 +36,12 @@
 
 #endif /* __alloc_objs */
 
+/*
+ * struct sockaddr_unsized was introduced in Linux 7.0 to replace struct sockaddr
+ * in proto_ops .bind/.connect callbacks. Map it to struct sockaddr on older kernels.
+ */
+#if LINUX_VERSION_CODE < KERNEL_VERSION(7, 0, 0)
+#define sockaddr_unsized sockaddr
+#endif
+
 #endif /* _MOD_ORPHAN_COMPAT_H */

net/rose/Kbuild

@@ -1,5 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
 
+ccflags-y += -include $(src)/../../include/hamradio_compat.h
+
 obj-m += rose.o
 
 rose-y := af_rose.o rose_dev.o rose_in.o rose_link.o rose_loopback.o \

net/rose/rose_in.c

@@ -57,6 +57,7 @@ static int rose_state1_machine(struct sock *sk, struct sk_buff *skb, int framety
 		rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
 		rose_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]);
 		rose_neigh_put(rose->neighbour);
+		rose->neighbour = NULL;
 		break;
 
 	default:
@@ -80,11 +81,13 @@ static int rose_state2_machine(struct sock *sk, struct sk_buff *skb, int framety
 		rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
 		rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
 		rose_neigh_put(rose->neighbour);
+		rose->neighbour = NULL;
 		break;
 
 	case ROSE_CLEAR_CONFIRMATION:
 		rose_disconnect(sk, 0, -1, -1);
 		rose_neigh_put(rose->neighbour);
+		rose->neighbour = NULL;
 		break;
 
 	default:
@@ -121,6 +124,7 @@ static int rose_state3_machine(struct sock *sk, struct sk_buff *skb, int framety
 		rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
 		rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
 		rose_neigh_put(rose->neighbour);
+		rose->neighbour = NULL;
 		break;
 
 	case ROSE_RR:
@@ -234,6 +238,7 @@ static int rose_state4_machine(struct sock *sk, struct sk_buff *skb, int framety
 		rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
 		rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
 		rose_neigh_put(rose->neighbour);
+		rose->neighbour = NULL;
 		break;
 
 	default:
@@ -254,6 +259,7 @@ static int rose_state5_machine(struct sock *sk, struct sk_buff *skb, int framety
 		rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
 		rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
 		rose_neigh_put(rose_sk(sk)->neighbour);
+		rose_sk(sk)->neighbour = NULL;
 	}
 
 	return 0;

net/rose/rose_loopback.c

@@ -12,13 +12,15 @@
 #include <net/rose.h>
 #include <linux/init.h>
 
-static struct sk_buff_head loopback_queue;
 #define ROSE_LOOPBACK_LIMIT 1000
-static struct timer_list loopback_timer;
 
+static struct timer_list loopback_timer;
+static struct sk_buff_head loopback_queue;
 static void rose_set_loopback_timer(void);
 static void rose_loopback_timer(struct timer_list *unused);
 
+static atomic_t loopback_stopping = ATOMIC_INIT(0);
+
 void rose_loopback_init(void)
 {
 	skb_queue_head_init(&loopback_queue);
@@ -66,10 +68,25 @@ static void rose_loopback_timer(struct timer_list *unused)
 	unsigned int lci_i, lci_o;
 	int count;
 
+	if (atomic_read(&loopback_stopping))
+		return;
+
+	if (rose_loopback_neigh)
+		rose_neigh_hold(rose_loopback_neigh);
+	else
+		return;
+
 	for (count = 0; count < ROSE_LOOPBACK_LIMIT; count++) {
 		skb = skb_dequeue(&loopback_queue);
 		if (!skb)
-			return;
+			goto out;
+
+		if (atomic_read(&loopback_stopping)) {
+			kfree_skb(skb);
+			skb_queue_purge(&loopback_queue);
+			goto out;
+		}
+
 		if (skb->len < ROSE_MIN_LEN) {
 			kfree_skb(skb);
 			continue;
@@ -96,38 +113,40 @@ static void rose_loopback_timer(struct timer_list *unused)
 		}
 
 		if (frametype == ROSE_CALL_REQUEST) {
-			if (!rose_loopback_neigh->dev &&
-			    !rose_loopback_neigh->loopback) {
-				kfree_skb(skb);
-				continue;
-			}
-
 			dev = rose_dev_get(dest);
 			if (!dev) {
 				kfree_skb(skb);
 				continue;
 			}
 
-			if (rose_rx_call_request(skb, dev, rose_loopback_neigh, lci_o) == 0) {
-				dev_put(dev);
+			if (rose_rx_call_request(skb, dev, rose_loopback_neigh, lci_o) == 0)
 				kfree_skb(skb);
-			}
+			dev_put(dev);
 		} else {
 			kfree_skb(skb);
 		}
 	}
-	if (!skb_queue_empty(&loopback_queue))
+
+out:
+	rose_neigh_put(rose_loopback_neigh);
+
+	if (!atomic_read(&loopback_stopping) && !skb_queue_empty(&loopback_queue))
 		mod_timer(&loopback_timer, jiffies + 1);
 }
 
 void __exit rose_loopback_clear(void)
 {
 	struct sk_buff *skb;
 
-	timer_delete(&loopback_timer);
+	atomic_set(&loopback_stopping, 1);
+	/* Pairs with atomic_read() in rose_loopback_timer(): ensure the
+	 * stopping flag is visible before we cancel, so a concurrent
+	 * callback aborts its loop early rather than re-arming the timer.
+	 */
+	smp_mb();
 
-	while ((skb = skb_dequeue(&loopback_queue)) != NULL) {
-		skb->sk = NULL;
+	timer_delete_sync(&loopback_timer);
+
+	while ((skb = skb_dequeue(&loopback_queue)) != NULL)
 		kfree_skb(skb);
-	}
 }

net/rose/rose_timer.c

@@ -180,7 +180,10 @@ static void rose_timer_expiry(struct timer_list *t)
 		break;
 
 	case ROSE_STATE_2:	/* T3 */
-		rose_neigh_put(rose->neighbour);
+		if (rose->neighbour) {
+			rose_neigh_put(rose->neighbour);
+			rose->neighbour = NULL;
+		}
 		rose_disconnect(sk, ETIMEDOUT, -1, -1);
 		break;