sqlite-deserialize-repro

Reproduces a heap-buffer-overflow in SQLite's sqlite3SchemaToIndex(). It is triggered by querying an eponymous virtual table (json_each, pragma_*, dbstat, or a module registered with sqlite3_create_module()) before and after sqlite3_deserialize() on "main".

sqlite3VtabEponymousTableInit() stores db->aDb[0].pSchema in the eponymous table once. sqlite3_deserialize() frees that Schema and installs a new one, so the next query's sqlite3SchemaToIndex() never finds the stale pointer and reads past the end of db->aDb[].

Found while testing @photostructure/sqlite.

Run it

Needs make, curl, tar, patch, and a C compiler with AddressSanitizer.

make test     # fails: ASan heap-buffer-overflow
make fix      # applies fix.diff to ./sqlite
make test     # passes
make unfix    # reverts fix.diff

make test downloads SQLite check-in 65ec11f05a (trunk, 2026-10-02) into ./sqlite, builds the amalgamation, and runs repro.c twice:

• under AddressSanitizer, which reports the overflow;
• with -DSQLITE_DEBUG, where assert( i<db->nDb ) in sqlite3SchemaToIndex() fails.

To test current trunk: make clean && make test CHECKIN=trunk.

Files

• repro.c: the reproduction.
• fix.diff: a candidate fix to src/attach.c that clears the eponymous tables when sqlite3_deserialize() reopens main. Offered as documentation of what we tried, not as a proposed patch.
• Makefile: the test, fix, unfix, and clean targets.

License

CC0 1.0. To the extent possible under law, PhotoStructure Inc. has waived all copyright and related or neighboring rights to this work.