[all-commits] [llvm/llvm-project] 7f69c8: [llvm-special-case-list-fuzzer] fix off-by-one rea...

[DavidKorczynski via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 7f69c8b3a6c02ea32fefb16c2016dfa1ba994858
      https://github.com/llvm/llvm-project/commit/7f69c8b3a6c02ea32fefb16c2016dfa1ba994858
  Author: DavidKorczynski <david at adalogics.com>
  Date:   2023-12-28 (Thu, 28 Dec 2023)

  Changed paths:
    M llvm/tools/llvm-special-case-list-fuzzer/special-case-list-fuzzer.cpp

  Log Message:
  -----------
  [llvm-special-case-list-fuzzer] fix off-by-one read (#73888)

The current fuzzer relies on MemoryBuffer to hold the fuzz data.
However, the fuzzer runs into an OOB instantly because the MemoryBuffer
interface guarantees that "In addition to basic access to the characters
in the file, this interface guarantees you can read one character past
the end of the file, and that this character will read as '\0'."
[ref](https://llvm.org/doxygen/classllvm_1_1MemoryBuffer.html#details),
which the fuzzer fails to satisfy. As such, it runs into an OOB on [this
line](https://github.com/llvm/llvm-project/blob/c57ef2c69846a3f69c9d1db61055ea3b7b5100c3/llvm/lib/Support/LineIterator.cpp#L48).

Consequently, the OSS-Fuzz set up is not running since the build is
declared failing as the fuzzer fails on the first run. See here for
links to build logs
https://introspector.oss-fuzz.com/project-profile?project=llvm and
specifically at the bottom of [this build
log](https://oss-fuzz-build-logs.storage.googleapis.com/log-aecaad16-9581-48fe-af4a-a7be4dd947db.txt).

This change fixes the fuzzer and should solve the OSS-Fuzz build as
well.

Signed-off-by: David Korczynski <david at adalogics.com>