Add missing check for corrupted central directory

[alinpahontu2912]

Fixes #131228

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[Copilot]

Pull request overview

This PR hardens System.IO.Compression ZIP reading for AES-encrypted entries by avoiding an unexpected ArgumentOutOfRangeException when a corrupted central directory points a local-header offset past the end of the archive. Instead of failing during central directory parsing (when salts are eagerly read), the error is deferred until the entry is opened, aligning AES behavior with non-encrypted entries.

Changes:

• Add an early “offset past end-of-stream” guard in AES salt pre-read logic (sync + async) to avoid Seek throwing on some stream types (e.g., MemoryStream).
• Add a regression test that corrupts a central directory record’s local header offset and verifies enumeration doesn’t throw unexpectedly, while Open() still fails with InvalidDataException.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
src/libraries/System.IO.Compression/tests/ZipArchive/zip_InvalidParametersAndStrangeFiles.cs	Adds a regression test ensuring central directory parsing doesn’t throw unexpectedly for a corrupted AES entry offset and that failure is deferred to entry open.
src/libraries/System.IO.Compression/src/System/IO/Compression/ZipArchiveEntry.cs	Adds a length-based guard in ReadEncryptionSaltIfNeeded to prevent Seek-triggered ArgumentOutOfRangeException during central directory parsing.
src/libraries/System.IO.Compression/src/System/IO/Compression/ZipArchiveEntry.Async.cs	Mirrors the same guard for the async salt pre-read path.

[rzikm]

LGTM, I assume you ran the fuzzer locally to confirm there aren't other bugs still lurking?

[alinpahontu2912]

Yep, I ran it locally and it worked. Also ran it against the faulty input directly

[MihaZupan]

Thank you.
Let me see if this command still works:
@MihuBot fuzz ZipArchive

[MihuBot]

Ran the fuzzer(s) successfully. Code coverage reports:

• ZipArchiveFuzzer

[alinpahontu2912]

/ba-g failures are unrelated to my change