Fuzzing Crash: AssertionFailed in file_io

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Fuzzing Crash Report

Analysis

Crash Location: fuzz/fuzz_targets/file_io.rs:100:__libfuzzer_sys_run

Error Message:

assertion `left == right` failed: Length was not preserved expected 6 actual 0.
  left: 6
 right: 0

Stack Trace

stack backtrace:
   0: __rustc::rust_begin_unwind
             at /rustc/db3e99bbab28c6ca778b13222becdea54533d908/library/std/src/panicking.rs:689:5
   1: core::panicking::panic_fmt
             at /rustc/db3e99bbab28c6ca778b13222becdea54533d908/library/core/src/panicking.rs:80:14
   2: core::panicking::assert_failed_inner
   3: core::panicking::assert_failed::<usize, usize>
             at /rustc/db3e99bbab28c6ca778b13222becdea54533d908/library/core/src/panicking.rs:394:5
   4: __libfuzzer_sys_run
             at ./fuzz/fuzz_targets/file_io.rs:100:5
   5: rust_fuzzer_test_input
             at /home/runner/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/libfuzzer-sys-0.4.12/src/lib.rs:363:60
   6: {closure#0}
             at /home/runner/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/libfuzzer-sys-0.4.12/src/lib.rs:62:9
   7: do_call<libfuzzer_sys::test_input_wrap::{closure_env#0}, i32>
             at /rustc/db3e99bbab28c6ca778b13222becdea54533d908/library/std/src/panicking.rs:581:40
   8: __rust_try
   9: catch_unwind<i32, libfuzzer_sys::test_input_wrap::{closure_env#0}>
             at /rustc/db3e99bbab28c6ca778b13222becdea54533d908/library/std/src/panicking.rs:544:19
  10: catch_unwind<libfuzzer_sys::test_input_wrap::{closure_env#0}, i32>
             at /rustc/db3e99bbab28c6ca778b13222becdea54533d908/library/std/src/panic.rs:359:14
  11: test_input_wrap
             at /home/runner/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/libfuzzer-sys-0.4.12/src/lib.rs:60:22
  12: _ZN6fuzzer6Fuzzer15ExecuteCallbackEPKhm
             at /home/runner/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/libfuzzer-sys-0.4.12/libfuzzer/FuzzerLoop.cpp:619:13
  13: _ZN6fuzzer10RunOneTestEPNS_6FuzzerEPKcm
             at /home/runner/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/libfuzzer-sys-0.4.12/libfuzzer/FuzzerDriver.cpp:335:6
  14: _ZN6fuzzer12FuzzerDriverEPiPPPcPFiPKhmE
             at /home/runner/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/libfuzzer-sys-0.4.12/libfuzzer/FuzzerDriver.cpp:871:9
  15: main
             at /home/runner/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/libfuzzer-sys-0.4.12/libfuzzer/FuzzerMain.cpp:20:10
  16: <unknown>
  17: __libc_start_main
  18: _start

Root Cause Analysis

The crash is an assertion failure in the file_io fuzz target (fuzz/fuzz_targets/file_io.rs:100) where a round-trip through the Vortex file format loses all rows: the in-memory filtered/projected array has 6 elements but reading back from the written file with the same filter and projection returns 0 elements. The root cause is likely a bug in the scan-path filter pushdown logic (in vortex-scan or vortex-layout) where row group or chunk statistics are used to prune data during read — the pruning incorrectly eliminates all chunks that actually contain matching rows, producing an empty result. The fix should investigate how zone maps or per-chunk statistics interact with the fuzzed filter expression during scan, particularly for edge cases around nullable columns, boundary values, or compound filter predicates that may cause the pruning predicate to be overly aggressive.

Summary

• Target: file_io
• Crash File: crash-a15dea563e219f79970ff219d222bd34d7f3b0f9
• Branch: develop
• Commit: dbfe521
• Crash Artifact: https://github.com/vortex-data/vortex/actions/runs/26449115165/artifacts/7217603479

Reproduce

cargo +nightly fuzz run -D --sanitizer=none file_io ./fuzz/artifacts/file_io/crash-a15dea563e219f79970ff219d222bd34d7f3b0f9 -- -rss_limit_mb=0

Reproduction Steps

1. Download the crash artifact: https://github.com/vortex-data/vortex/actions/runs/26449115165/artifacts/7217603479

2. Assuming you download the zipfile to ~/Downloads, and your working directory is the repository root:

# Create the artifacts directory if you haven't already.
mkdir -p ./fuzz/artifacts

# Move the zipfile.
mv ~/Downloads/file_io-crash-artifacts.zip ./fuzz/artifacts/

# Unzip the zipfile.
unzip ./fuzz/artifacts/file_io-crash-artifacts.zip -d ./fuzz/artifacts/

# You can remove the zipfile now if you want to.
rm ./fuzz/artifacts/file_io-crash-artifacts.zip

3. Reproduce the crash:

cargo +nightly fuzz run -D --sanitizer=none file_io ./fuzz/artifacts/file_io/crash-a15dea563e219f79970ff219d222bd34d7f3b0f9 -- -rss_limit_mb=0

If you want a backtrace:

RUST_BACKTRACE=1 cargo +nightly fuzz run -D --sanitizer=none file_io ./fuzz/artifacts/file_io/crash-a15dea563e219f79970ff219d222bd34d7f3b0f9 -- -rss_limit_mb=0

RUST_BACKTRACE=full cargo +nightly fuzz run -D --sanitizer=none file_io ./fuzz/artifacts/file_io/crash-a15dea563e219f79970ff219d222bd34d7f3b0f9 -- -rss_limit_mb=0

Single command to get a backtrace

mkdir -p ./fuzz/artifacts
mv ~/Downloads/file_io-crash-artifacts.zip ./fuzz/artifacts/
unzip ./fuzz/artifacts/file_io-crash-artifacts.zip -d ./fuzz/artifacts/
rm ./fuzz/artifacts/file_io-crash-artifacts.zip
RUST_BACKTRACE=1 cargo +nightly fuzz run -D --sanitizer=none file_io ./fuzz/artifacts/file_io/crash-a15dea563e219f79970ff219d222bd34d7f3b0f9 -- -rss_limit_mb=0

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