@matheusbsbs / matheus-bagliano / commits / 4c490f3d32

split-index: BUG() when cache entry refers to non-existing shared entry

When the split index feature is in use, then a cache entry is: - either only present in the split index, in which case its 'index' field must be 0, - or it should refer to an existing entry in the shared index, i.e. the 'index' field can't be greater than the size of the shared index. If a cache entry were to refer to a non-existing entry in the shared index, then that's a sign of something being wrong in the index state, either as a result of a bug in dealing with the split/shared index entries, or perhaps a (potentially unrelated) memory corruption issue. prepare_to_write_split_index() already has a condition to catch cache entries with such bogus 'index' field, but instead of calling BUG() it just sets cache entry's 'index = 0', and the entry will then be written to the new split index. Don't write a new index file from bogus index state, and call BUG() upon encountering an cache entry referring to a non-existing shared index entry. Running the test suite repeatedly with 'GIT_TEST_SPLIT_INDEX=yes' doesn't trigger this condition. Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>

SZEDER Gábor committed Oct 11, 2018 at 11:53 UTC 4c490f3d321da415b8d3bec4a04565906657b9c9

1 file changed +2 -2

split-index.c

+2 -2

@@ -254,8 +254,8 @@ void prepare_to_write_split_index(struct index_state *istate)

254 continue;

255 }

256 if (ce->index > si->base->cache_nr) {

257 - ce->index = 0;

258 - continue;

257 + BUG("ce refers to a shared ce at %d, which is beyond the shared index size %d",

258 + ce->index, si->base->cache_nr);

259 }

260 ce->ce_flags |= CE_MATCHED; /* or "shared" */

261 base = si->base->cache[ce->index - 1];