[PATCH 4.9 133/191] net: fix memleak in register_netdevice()

Sasha Levin
2020-06-29T20:31:18Z

From: Yang Yingliang <yangyingliang@huawei.com>

[ Upstream commit 814152a89ed52c722ab92e9fbabcac3cb8a39245 ]

I got a memleak report when doing some fuzz test:

unreferenced object 0xffff888112584000 (size 13599):
comm "ip", pid 3048, jiffies 4294911734 (age 343.491s)
hex dump (first 32 bytes):
74 61 70 30 00 00 00 00 00 00 00 00 00 00 00 00 tap0............
00 ee d9 19 81 88 ff ff 00 00 00 00 00 00 00 00 ................
backtrace:
[<000000002f60ba65>] __kmalloc_node+0x309/0x3a0
[<0000000075b211ec>] kvmalloc_node+0x7f/0xc0
[<00000000d3a97396>] alloc_netdev_mqs+0x76/0xfc0
[<00000000609c3655>] __tun_chr_ioctl+0x1456/0x3d70
[<000000001127ca24>] ksys_ioctl+0xe5/0x130
[<00000000b7d5e66a>] __x64_sys_ioctl+0x6f/0xb0
[<00000000e1023498>] do_syscall_64+0x56/0xa0
[<000000009ec0eb12>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
unreferenced object 0xffff888111845cc0 (size 8):
comm "ip", pid 3048, jiffies 4294911734 (age 343.491s)
hex dump (first 8 bytes):
74 61 70 30 00 88 ff ff tap0....
backtrace:
[<000000004c159777>] kstrdup+0x35/0x70
[<00000000d8b496ad>] kstrdup_const+0x3d/0x50
[<00000000494e884a>] kvasprintf_const+0xf1/0x180
[<0000000097880a2b>] kobject_set_name_vargs+0x56/0x140
[<000000008fbdfc7b>] dev_set_name+0xab/0xe0
[<000000005b99e3b4>] netdev_register_kobject+0xc0/0x390
[<00000000602704fe>] register_netdevice+0xb61/0x1250
[<000000002b7ca244>] __tun_chr_ioctl+0x1cd1/0x3d70
[<000000001127ca24>] ksys_ioctl+0xe5/0x130
[<00000000b7d5e66a>] __x64_sys_ioctl+0x6f/0xb0
[<00000000e1023498>] do_syscall_64+0x56/0xa0
[<000000009ec0eb12>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
unreferenced object 0xffff88811886d800 (size 512):
comm "ip", pid 3048, jiffies 4294911734 (age 343.491s)
hex dump (first 32 bytes):
00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00 .....N..........
ff ff ff ff ff ff ff ff c0 66 3d a3 ff ff ff ff .........f=.....
backtrace:
[<0000000050315800>] device_add+0x61e/0x1950
[<0000000021008dfb>] netdev_register_kobject+0x17e/0x390
[<00000000602704fe>] register_netdevice+0xb61/0x1250
[<000000002b7ca244>] __tun_chr_ioctl+0x1cd1/0x3d70
[<000000001127ca24>] ksys_ioctl+0xe5/0x130
[<00000000b7d5e66a>] __x64_sys_ioctl+0x6f/0xb0
[<00000000e1023498>] do_syscall_64+0x56/0xa0
[<000000009ec0eb12>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

If call_netdevice_notifiers() failed, then rollback_registered()
calls netdev_unregister_kobject() which holds the kobject. The
reference cannot be put because the netdev won't be add to todo
list, so it will leads a memleak, we need put the reference to
avoid memleak.

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/core/dev.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/net/core/dev.c b/net/core/dev.c
index edb2ddbbed9a1..267b648a0645e 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -7355,6 +7355,13 @@ int register_netdevice(struct net_device *dev)
rcu_barrier();

dev->reg_state = NETREG_UNREGISTERED;
+ /* We should put the kobject that hold in
+ * netdev_unregister_kobject(), otherwise
+ * the net device cannot be freed when
+ * driver calls free_netdev(), because the
+ * kobject is being hold.
+ */
+ kobject_put(&dev->dev.kobj);
}
/*
* Prevent userspace races by waiting until the network
--
2.25.1