tests: Add regression tests for ec_privkey_import_der() rejecting malformed input #1895

pull cavdarahmet wants to merge 1 commits into bitcoin-core:master from cavdarahmet:test-privkey-import-der-invalid changing 1 files +54 −0

cavdarahmet commented at 8:00 PM on July 22, 2026: none

ec_privkey_import_der() has 8 distinct structural checks that reject malformed DER private key encodings (wrong sequence tag, bad length encoding, wrong version field, bad octet string tag/length, and truncation at any point). None of these rejection paths were covered by any existing test -- only the successful round-trip path was exercised.

I fuzzed this function extensively (truncation at every length, single-bit mutation at every byte position, all under ASan/UBSan) and found no memory-safety or logic bugs -- the checks are correct as written. This PR only adds regression coverage so that a future refactor can't silently reintroduce a parsing bug here.

tests: Add regression tests for ec_privkey_import_der() rejecting malformed input

The function's structural validation checks (sequence tag, length
encoding, version field, octet string tag/length, truncation) were
never exercised by any test -- only the success path was covered.

Add a test that verifies each rejection path triggers on the
corresponding malformed input, plus full-truncation coverage at
every length.

03ec050a3e

Contributors

cavdarahmet