feat: add max slice alloc size config

codec_array.go

@@ -39,10 +39,6 @@ type arrayDecoder struct {
  decoder ValDecoder
 }
 
-// Max allocation size for an array due to the limit in number of bits in a heap address:
-// https://github.com/golang/go/blob/7f76c00fc5678fa782708ba8fece63750cb89d03/src/runtime/malloc.go#L183
-var maxAllocSize = uint64(1 << 48)
-
 func (d *arrayDecoder) Decode(ptr unsafe.Pointer, r *Reader) {
  var size int
  sliceType := d.typ
@@ -55,10 +51,12 @@ func (d *arrayDecoder) Decode(ptr unsafe.Pointer, r *Reader) {
 
  start := size
  size += int(l)
- if size > int(maxAllocSize) {
- r.ReportError("decode array", "size exceeded max allocation size")
+
+ if size > r.cfg.getMaxSliceAllocSize() {
+ r.ReportError("decode array", "size is greater than `Config.MaxSliceAllocSize`")
  return
  }
+
  sliceType.UnsafeGrow(ptr, size)
 
  for i := start; i < size; i++ {

config.go

@@ -8,7 +8,12 @@ import (
  "github.com/modern-go/reflect2"
 )
 
-const defaultMaxByteSliceSize = 1_048_576 // 1 MiB
+const (
+ defaultMaxByteSliceSize = 1_048_576 // 1 MiB
+ // Max allocation size for an array due to the limit in number of bits in a heap address:
+ // https://github.com/golang/go/blob/7f76c00fc5678fa782708ba8fece63750cb89d03/src/runtime/malloc.go#L183
+ maxAllocSize = int(1 << 48)
+)
 
 // DefaultConfig is the default API.
 var DefaultConfig = Config{}.Freeze()
@@ -49,6 +54,11 @@ type Config struct {
  // MaxByteSliceSize is the maximum size of `bytes` or `string` types the Reader will create, defaulting to 1MiB.
  // If this size is exceeded, the Reader returns an error. This can be disabled by setting a negative number.
  MaxByteSliceSize int
+
+ // MaxSliceAllocSize is the maximum size that the decoder will allocate, set to the max heap
+ // allocation size by default.
+ // If this size is exceeded, the decoder returns an error.
+ MaxSliceAllocSize int
 }
 
 // Freeze makes the configuration immutable.
@@ -266,3 +276,11 @@ func (c *frozenConfig) getMaxByteSliceSize() int {
  }
  return size
 }
+
+func (c *frozenConfig) getMaxSliceAllocSize() int {
+ size := c.config.MaxSliceAllocSize
+ if size > maxAllocSize || size <= 0 {
+ return maxAllocSize
+ }
+ return size
+}

decoder_array_test.go

@@ -91,3 +91,18 @@ func TestDecoder_ArrayMaxAllocationError(t *testing.T) {
 
  assert.Error(t, err)
 }
+
+func TestDecoder_ArrayExceedMaxSliceAllocationConfig(t *testing.T) {
+ avro.DefaultConfig = avro.Config{MaxSliceAllocSize: 5}.Freeze()
+
+ // 10 (long) gets encoded to 0x14
+ data := []byte{0x14}
+ schema := `{"type":"array", "items": { "type": "boolean" }}`
+ dec, err := avro.NewDecoder(schema, bytes.NewReader(data))
+ require.NoError(t, err)
+
+ var got []bool
+ err = dec.Decode(&got)
+
+ assert.Error(t, err)
+}