Re: [PATCH] hv_netvsc: Fix memory leak when removing rndis device
From: Stephen Hemminger <stephen@networkplumber.org>
Date: 2020-01-13 20:03:07
Also in:
lkml, netdev
On Mon, 13 Jan 2020 21:27:52 +0200 Mohammed Gamal [off-list ref] wrote:
quoted hunk ↗ jump to hunk
kmemleak detects the following memory leak when hot removing a network device: unreferenced object 0xffff888083f63600 (size 256): comm "kworker/0:1", pid 12, jiffies 4294831717 (age 1113.676s) hex dump (first 32 bytes): 00 40 c7 33 80 88 ff ff 00 00 00 00 10 00 00 00 .@.3............ 00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00 .....N.......... backtrace: [<00000000d4a8f5be>] rndis_filter_device_add+0x117/0x11c0 [hv_netvsc] [<000000009c02d75b>] netvsc_probe+0x5e7/0xbf0 [hv_netvsc] [<00000000ddafce23>] vmbus_probe+0x74/0x170 [hv_vmbus] [<00000000046e64f1>] really_probe+0x22f/0xb50 [<000000005cc35eb7>] driver_probe_device+0x25e/0x370 [<0000000043c642b2>] bus_for_each_drv+0x11f/0x1b0 [<000000005e3d09f0>] __device_attach+0x1c6/0x2f0 [<00000000a72c362f>] bus_probe_device+0x1a6/0x260 [<0000000008478399>] device_add+0x10a3/0x18e0 [<00000000cf07b48c>] vmbus_device_register+0xe7/0x1e0 [hv_vmbus] [<00000000d46cf032>] vmbus_add_channel_work+0x8ab/0x1770 [hv_vmbus] [<000000002c94bb64>] process_one_work+0x919/0x17d0 [<0000000096de6781>] worker_thread+0x87/0xb40 [<00000000fbe7397e>] kthread+0x333/0x3f0 [<000000004f844269>] ret_from_fork+0x3a/0x50 rndis_filter_device_add() allocates an instance of struct rndis_device which never gets deallocated and rndis_filter_device_remove() sets net_device->extension which points to the rndis_device struct to NULL without ever freeing the structure first, leaving it dangling. This patch fixes this by freeing the structure before setting net_device->extension to NULL Signed-off-by: Mohammed Gamal <redacted> --- drivers/net/hyperv/rndis_filter.c | 1 + 1 file changed, 1 insertion(+)diff --git a/drivers/net/hyperv/rndis_filter.c b/drivers/net/hyperv/rndis_filter.c index 857c4bea451c..d2e094f521a4 100644 --- a/drivers/net/hyperv/rndis_filter.c +++ b/drivers/net/hyperv/rndis_filter.c@@ -1443,6 +1443,7 @@ void rndis_filter_device_remove(struct hv_device *dev, /* Halt and release the rndis device */ rndis_filter_halt_device(net_dev, rndis_dev); + kfree(rndis_dev); net_dev->extension = NULL; netvsc_device_remove(dev);
That is one way, but maybe safer to just remove the line that sets
extension to NULL. That way netvsc_device_remove will clean it up:
netvsc_device_remove -> free_netvsc_device_rcu -> free_netvsc_device.