netdev - [PATCH] net-sysfs: Fix memory leak in register_queue

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Message-Id: <20191114111325.2027-1-jouni.hogander@unikie.com>
Date:   Thu, 14 Nov 2019 13:13:25 +0200
From:   jouni.hogander@...kie.com
To:     netdev@...r.kernel.org
Cc:     Jouni Hogander <jouni.hogander@...kie.com>,
        David Miller <davem@...emloft.net>,
        Lukas Bulwahn <lukas.bulwahn@...il.com>
Subject: [PATCH] net-sysfs: Fix memory leak in register_queue_kobjects

From: Jouni Hogander <jouni.hogander@...kie.com>

net_rx_queue_update_kobjects and netdev_queue_update_kobjects are
leaking memory in their error paths. Leak was originally reported
by Syzkaller:

BUG: memory leak
unreferenced object 0xffff8880679f8b08 (size 8):
  comm "netdev_register", pid 269, jiffies 4294693094 (age 12.132s)
  hex dump (first 8 bytes):
    72 78 2d 30 00 36 20 d4                          rx-0.6 .
  backtrace:
    [<000000008c93818e>] __kmalloc_track_caller+0x16e/0x290
    [<000000001f2e4e49>] kvasprintf+0xb1/0x140
    [<000000007f313394>] kvasprintf_const+0x56/0x160
    [<00000000aeca11c8>] kobject_set_name_vargs+0x5b/0x140
    [<0000000073a0367c>] kobject_init_and_add+0xd8/0x170
    [<0000000088838e4b>] net_rx_queue_update_kobjects+0x152/0x560
    [<000000006be5f104>] netdev_register_kobject+0x210/0x380
    [<00000000e31dab9d>] register_netdevice+0xa1b/0xf00
    [<00000000f68b2465>] __tun_chr_ioctl+0x20d5/0x3dd0
    [<000000004c50599f>] tun_chr_ioctl+0x2f/0x40
    [<00000000bbd4c317>] do_vfs_ioctl+0x1c7/0x1510
    [<00000000d4c59e8f>] ksys_ioctl+0x99/0xb0
    [<00000000946aea81>] __x64_sys_ioctl+0x78/0xb0
    [<0000000038d946e5>] do_syscall_64+0x16f/0x580
    [<00000000e0aa5d8f>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
    [<00000000285b3d1a>] 0xffffffffffffffff

Cc: David Miller <davem@...emloft.net>
Cc: Lukas Bulwahn <lukas.bulwahn@...il.com>
Signed-off-by: Jouni Hogander <jouni.hogander@...kie.com>
---
 net/core/net-sysfs.c | 34 ++++++++++++++++++++++++----------
 1 file changed, 24 insertions(+), 10 deletions(-)

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 865ba6ca16eb..2f44c6a3bcae 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -923,20 +923,25 @@ static int rx_queue_add_kobject(struct net_device *dev, int index)
 	error = kobject_init_and_add(kobj, &rx_queue_ktype, NULL,
 				     "rx-%u", index);
 	if (error)
-		return error;
+		goto err_init_and_add;
 
 	dev_hold(queue->dev);
 
 	if (dev->sysfs_rx_queue_group) {
 		error = sysfs_create_group(kobj, dev->sysfs_rx_queue_group);
-		if (error) {
-			kobject_put(kobj);
-			return error;
-		}
+		if (error)
+			goto err_sysfs_create;
 	}
 
 	kobject_uevent(kobj, KOBJ_ADD);
 
+	return error;
+
+err_sysfs_create:
+	kobject_put(kobj);
+err_init_and_add:
+	kfree_const(kobj->name);
+
 	return error;
 }
 #endif /* CONFIG_SYSFS */
@@ -968,6 +973,7 @@ net_rx_queue_update_kobjects(struct net_device *dev, int old_num, int new_num)
 		if (dev->sysfs_rx_queue_group)
 			sysfs_remove_group(kobj, dev->sysfs_rx_queue_group);
 		kobject_put(kobj);
+		kfree_const(kobj->name);
 	}
 
 	return error;
@@ -1461,21 +1467,28 @@ static int netdev_queue_add_kobject(struct net_device *dev, int index)
 	error = kobject_init_and_add(kobj, &netdev_queue_ktype, NULL,
 				     "tx-%u", index);
 	if (error)
-		return error;
+		goto err_init_and_add;
 
 	dev_hold(queue->dev);
 
 #ifdef CONFIG_BQL
 	error = sysfs_create_group(kobj, &dql_group);
-	if (error) {
-		kobject_put(kobj);
-		return error;
-	}
+	if (error)
+		goto err_sysfs_create;
 #endif
 
 	kobject_uevent(kobj, KOBJ_ADD);
 
 	return 0;
+
+#ifdef CONFIG_BQL
+err_sysfs_create:
+	kobject_put(kobj);
+#endif
+err_init_and_add:
+	kfree_const(kobj->name);
+
+	return error;
 }
 #endif /* CONFIG_SYSFS */
 
@@ -1503,6 +1516,7 @@ netdev_queue_update_kobjects(struct net_device *dev, int old_num, int new_num)
 		sysfs_remove_group(&queue->kobj, &dql_group);
 #endif
 		kobject_put(&queue->kobj);
+		kfree_const(queue->kobj.name);
 	}
 
 	return error;
-- 
2.17.1