Created
January 31, 2019 19:06
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Go reflect.MakeFunc crash reproduction
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package main | |
import ( | |
"context" | |
"log" | |
"os" | |
"os/signal" | |
"reflect" | |
"strings" | |
"syscall" | |
"time" | |
) | |
func NewFlag(getFuncVar interface{}) interface{} { | |
fv := reflect.ValueOf(getFuncVar) | |
ft := fv.Type().Elem() | |
fv.Elem().Set(reflect.MakeFunc(ft, func(args []reflect.Value) []reflect.Value { | |
value := (*A)(nil) | |
return []reflect.Value{reflect.ValueOf(value)} | |
})) | |
return nil | |
} | |
var ( | |
SomeFlagOverride func(context.Context) *A | |
_ = NewFlag(&SomeFlagOverride) | |
) | |
func ptrString(x string) *string { return &x } | |
func main() { | |
c := context.Background() | |
GetSomeFlag := func(c context.Context) *string { | |
override := SomeFlagOverride(c) | |
if override != nil { | |
return ptrString(override.A) | |
} | |
s := GetFlags().SomeFlag.A | |
return ptrString(s) | |
} | |
log.Printf("starting...") | |
time.Sleep(1 * time.Second) | |
for i := 0; i < 10; i++ { | |
go func() { | |
for { | |
GetSomeFlag(c) | |
} | |
}() | |
} | |
sigs := make(chan os.Signal, 1) | |
signal.Notify(sigs, syscall.SIGTERM, syscall.SIGINT) | |
<-sigs | |
} | |
type Flags struct { | |
// This is the only flag we're interested in for the test | |
SomeFlag *A | |
// The rest are the fields are junk to excercise the GC | |
A *D | |
B *D | |
C *D | |
D *D | |
E *D | |
K1 [64]byte | |
K2 [64]byte | |
K3 [64]byte | |
K4 [64]byte | |
} | |
func GetFlags() Flags { | |
return Flags{ | |
SomeFlag: &A{ | |
A: "0123456789 abcdefghijklmnopqrstuvwxyz ABCDEFGHIJKLMNOPQRSTUVWXYZ", | |
}, | |
A: NewD(), | |
B: NewD(), | |
C: NewD(), | |
D: NewD(), | |
E: NewD(), | |
K1: [64]byte{ | |
0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, | |
0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, | |
0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, | |
0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, | |
}, | |
K2: [64]byte{ | |
0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, | |
0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, | |
0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, | |
0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, | |
}, | |
K3: [64]byte{ | |
0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, | |
0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, | |
0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, | |
0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, | |
}, | |
K4: [64]byte{ | |
0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, | |
0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, | |
0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, | |
0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, | |
}, | |
} | |
} | |
type A struct { | |
A string | |
B string | |
C string | |
D string | |
E string | |
} | |
func NewA() *A { | |
return &A{ | |
A: strings.Repeat("a", 20), | |
B: strings.Repeat("b", 20), | |
C: strings.Repeat("c", 20), | |
D: strings.Repeat("d", 20), | |
E: strings.Repeat("e", 20), | |
} | |
} | |
type B struct { | |
A *A | |
B *A | |
C *A | |
D *A | |
E *A | |
} | |
func NewB() *B { | |
return &B{ | |
A: NewA(), | |
B: NewA(), | |
C: NewA(), | |
D: NewA(), | |
E: NewA(), | |
} | |
} | |
type C struct { | |
A *B | |
B *B | |
C *B | |
D *B | |
E *B | |
} | |
func NewC() *C { | |
return &C{ | |
A: NewB(), | |
B: NewB(), | |
C: NewB(), | |
D: NewB(), | |
E: NewB(), | |
} | |
} | |
type D struct { | |
A *C | |
B *C | |
C *C | |
D *C | |
E *C | |
} | |
func NewD() *D { | |
return &D{ | |
A: NewC(), | |
B: NewC(), | |
C: NewC(), | |
D: NewC(), | |
E: NewC(), | |
} | |
} |
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