Found with ASan while feeding fuzz-style modules to wasm-objdump --debug:

==ERROR: AddressSanitizer: global-buffer-overflow
READ of size 144 at 0x... thread T0
    #5 wabt::BinaryReaderLogging::WriteIndent() binary-reader-logging.cc:75
    #6 wabt::BinaryReaderLogging::BeginGenericCustomSection(...)
0x... is located 0 bytes after global variable
  'WriteIndent()::s_indent' ... of size 143

WriteIndent emits the indent from a fixed 142-space buffer in chunks. The loop writes full blocks and shrinks i; the leftover write then passed indent_, the whole width, rather than i. Once the indent grows past the buffer that leftover write runs off the end. WatWriter::WriteIndent uses the same loop but writes the leftover count, so this was the odd one out.

How the indent gets that big: it rises by two on every section Begin. A custom name section whose sub-section size runs past the section end fails after BeginNamesSection, and objdump reads with stop_on_first_error and fail_on_custom_section_error both off, so the matching End callbacks never run and the indent leaks a little per bad section. Enough of them and it passes the buffer during the prepass logging.

Regression test added under test/binary-reader; it overruns without the change and is clean with it.