[PATCH 4.14 09/46] net-sysfs: Fix reference count leak in rx|netdev_queue_add_kobject

From: Greg Kroah-Hartman
Date: Tue Jan 28 2020 - 08:58:55 EST


From: Jouni Hogander <jouni.hogander@xxxxxxxxxx>

commit b8eb718348b8fb30b5a7d0a8fce26fb3f4ac741b upstream.

kobject_init_and_add takes reference even when it fails. This has
to be given up by the caller in error handling. Otherwise memory
allocated by kobject_init_and_add is never freed. Originally found
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@xxxxxxxxxxxxx>
Cc: Lukas Bulwahn <lukas.bulwahn@xxxxxxxxx>
Signed-off-by: Jouni Hogander <jouni.hogander@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
net/core/net-sysfs.c | 24 +++++++++++++-----------
1 file changed, 13 insertions(+), 11 deletions(-)

--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -915,21 +915,23 @@ static int rx_queue_add_kobject(struct n
error = kobject_init_and_add(kobj, &rx_queue_ktype, NULL,
"rx-%u", index);
if (error)
- return error;
+ goto err;

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;
}

kobject_uevent(kobj, KOBJ_ADD);

return error;
+
+err:
+ kobject_put(kobj);
+ return error;
}
#endif /* CONFIG_SYSFS */

@@ -1326,21 +1328,21 @@ static int netdev_queue_add_kobject(stru
error = kobject_init_and_add(kobj, &netdev_queue_ktype, NULL,
"tx-%u", index);
if (error)
- return error;
+ goto err;

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;
#endif

kobject_uevent(kobj, KOBJ_ADD);

- return 0;
+err:
+ kobject_put(kobj);
+ return error;
}
#endif /* CONFIG_SYSFS */