Got `NegativeArraySizeException` when calling `writeValueAsString()`

[klettier]

Hi,

I'm serializing an object containing 15M values

• Jackson version: 2.14.2

Stack trace

java.lang.NegativeArraySizeException: -1649955036
	at java.base/java.lang.AbstractStringBuilder.<init>(AbstractStringBuilder.java:86)
	at java.base/java.lang.StringBuilder.<init>(StringBuilder.java:116)
	at com.fasterxml.jackson.core.util.TextBuffer.contentsAsString(TextBuffer.java:455)
	at com.fasterxml.jackson.core.io.SegmentedStringWriter.getAndClear(SegmentedStringWriter.java:85)
	at com.fasterxml.jackson.databind.ObjectMapper.writeValueAsString(ObjectMapper.java:3875)

Looks like an int overflow somewhere in TextBuffer 👀

Minimal test case that reproduce the issue

  data class MyData(
      @JsonProperty("foo")
      val foo: Collection<Item> = emptyList(),

      @JsonProperty("bar")
      val bar: Collection<Item> = emptyList(),
  )

  data class Item(
      @JsonProperty("id")
      val id: String,

      @JsonProperty("value")
      val value: String,
  )

  @Test
  fun overflow() {
      val report = MyData(
          foo = (1..5_000_000).map { Item(UUID.randomUUID().toString(), UUID.randomUUID().toString()) },
          bar = (1..10_000_000).map {
              Item(
                  "foo=${UUID.randomUUID()}bar=${UUID.randomUUID()},barbar=${UUID.randomUUID()}",
                  UUID.randomUUID().toString(),
              )
          },
      )

      jacksonObjectMapper().writeValueAsString(report)
  }

Result

[pjfanning]

Can you provide a test case? - it would speed this along

[klettier]

Yes I'm working on it

[klettier]

Minimal Test case that reproduce the issue added

[pjfanning]

I debugged the test case and the issue is that the TextBuffer gets too big. StringBuilder will only support Integer.MAX_VALUE chars (approx 2Gb in utf-8 or ascii - 1 byte per char).

@cowtowncoder the _segmentSize in TextBuffer can turn negative when the int overflows. We could throw exceptions after any increments to _segmentSize if the value goes negative.

There is little benefit to making _segmentSize a long because in the end contentsAsString and contentsAsArray can only support cases where the size is <= Integer.MAX_SIZE.

[pjfanning]

This is basically the same issue as #351

[pjfanning]

I modified my test to write to a writeValue(OutputStream, value) instead (I used a FileOutputStream) and that successfully handled the large JSON. Writing to a String is basically limited to 2 billion chars.

[cowtowncoder]

Ok, will merge the fix. Thank you @pjfanning for the fix, @klettier for reporting it!