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device: fix possible deadlock in close method

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There is a possible deadlock in `device.Close()` when you try to close
the device very soon after its start. The problem is that two different
methods acquire the same locks in different order:

1. device.Close()
 - device.ipcMutex.Lock()
 - device.state.Lock()

2. device.changeState(deviceState)
 - device.state.Lock()
 - device.ipcMutex.Lock()

Reproducer:

    func TestDevice_deadlock(t *testing.T) {
    	d := randDevice(t)
    	d.Close()
    }

Problem:

    $ go clean -testcache && go test -race -timeout 3s -run TestDevice_deadlock ./device | grep -A 10 sync.runtime_SemacquireMutex
    sync.runtime_SemacquireMutex(0xc000117d20?, 0x94?, 0x0?)
            /usr/local/opt/go/libexec/src/runtime/sema.go:77 +0x25
    sync.(*Mutex).lockSlow(0xc000130518)
            /usr/local/opt/go/libexec/src/sync/mutex.go:171 +0x213
    sync.(*Mutex).Lock(0xc000130518)
            /usr/local/opt/go/libexec/src/sync/mutex.go:90 +0x55
    golang.zx2c4.com/wireguard/device.(*Device).Close(0xc000130500)
            /Users/martin.basovnik/git/basovnik/wireguard-go/device/device.go:373 +0xb6
    golang.zx2c4.com/wireguard/device.TestDevice_deadlock(0x0?)
            /Users/martin.basovnik/git/basovnik/wireguard-go/device/device_test.go:480 +0x2c
    testing.tRunner(0xc00014c000, 0x131d7b0)
    --
    sync.runtime_SemacquireMutex(0xc000130564?, 0x60?, 0xc000130548?)
            /usr/local/opt/go/libexec/src/runtime/sema.go:77 +0x25
    sync.(*Mutex).lockSlow(0xc000130750)
            /usr/local/opt/go/libexec/src/sync/mutex.go:171 +0x213
    sync.(*Mutex).Lock(0xc000130750)
            /usr/local/opt/go/libexec/src/sync/mutex.go:90 +0x55
    sync.(*RWMutex).Lock(0xc000130750)
            /usr/local/opt/go/libexec/src/sync/rwmutex.go:147 +0x45
    golang.zx2c4.com/wireguard/device.(*Device).upLocked(0xc000130500)
            /Users/martin.basovnik/git/basovnik/wireguard-go/device/device.go:179 +0x72
    golang.zx2c4.com/wireguard/device.(*Device).changeState(0xc000130500, 0x1)

Signed-off-by: Martin Basovnik <martin.basovnik@gmail.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
This commit is contained in:
Martin Basovnik 2023-11-10 11:10:12 +01:00 committed by Jason A. Donenfeld
parent 542e565baa
commit 12269c2761
1 changed files with 2 additions and 2 deletions
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4
device/device.go
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@ -368,10 +368,10 @@ func (device *Device) RemoveAllPeers() {
}
func (device *Device) Close() {
device.ipcMutex.Lock()
defer device.ipcMutex.Unlock()
device.state.Lock()
defer device.state.Unlock()
device.ipcMutex.Lock()
defer device.ipcMutex.Unlock()
if device.isClosed() {
return
}