To keep track of which object filters are allowed or not, 'git upload-pack' stores the name of each filter in a string_list, and sets it ->util pointer to be either 0 or 1, indicating whether it is banned or allowed. Later on, we attempt to clear that list, but we incorrectly ask for the util pointers to be free()'d, too. This behavior (introduced back in 6dd3456a8c (upload-pack.c: allow banning certain object filter(s), 2020-08-03)) leads to an invalid free, and causes us to crash. In order to trigger this, one needs to fetch from a server that (a) has at least one object filter allowed, and (b) issue a fetch that contains a subset of the allowed filters (i.e., we cannot ask for a banned filter, since this causes us to die() before we hit the bogus string_list_clear()). In that case, whatever banned filters exist will cause a noop free() (since those ->util pointers are set to 0), but the first allowed filter we try to free will crash us. We never noticed this in the tests because we didn't have an example of setting 'uploadPackFilter' configuration variables and then following up with a valid fetch. The first new 'git clone' prevents further regression here. For good measure on top, add a test which checks the same behavior at a tree depth greater than 0. Signed-off-by: Taylor Blau <me@xxxxxxxxxxxx> --- t/t5616-partial-clone.sh | 10 +++++++++- upload-pack.c | 2 +- 2 files changed, 10 insertions(+), 2 deletions(-) diff --git a/t/t5616-partial-clone.sh b/t/t5616-partial-clone.sh index f4d49d8335..5da945cf15 100755 --- a/t/t5616-partial-clone.sh +++ b/t/t5616-partial-clone.sh @@ -281,7 +281,15 @@ test_expect_success 'upload-pack limits tree depth filters' ' test_config -C srv.bare uploadpackfilter.tree.maxDepth 0 && test_must_fail ok=sigpipe git clone --no-checkout --filter=tree:1 \ "file://$(pwd)/srv.bare" pc3 2>err && - test_i18ngrep "tree filter allows max depth 0, but got 1" err + test_i18ngrep "tree filter allows max depth 0, but got 1" err && + + git clone --no-checkout --filter=tree:0 "file://$(pwd)/srv.bare" pc4 && + + test_config -C srv.bare uploadpackfilter.tree.maxDepth 5 && + git clone --no-checkout --filter=tree:5 "file://$(pwd)/srv.bare" pc5 && + test_must_fail ok=sigpipe git clone --no-checkout --filter=tree:6 \ + "file://$(pwd)/srv.bare" pc6 2>err && + test_i18ngrep "tree filter allows max depth 5, but got 6" err ' test_expect_success 'partial clone fetches blobs pointed to by refs even if normally filtered out' ' diff --git a/upload-pack.c b/upload-pack.c index 5dc8e1f844..d89c7e4a02 100644 --- a/upload-pack.c +++ b/upload-pack.c @@ -154,7 +154,7 @@ static void upload_pack_data_clear(struct upload_pack_data *data) string_list_clear(&data->deepen_not, 0); object_array_clear(&data->extra_edge_obj); list_objects_filter_release(&data->filter_options); - string_list_clear(&data->allowed_filters, 1); + string_list_clear(&data->allowed_filters, 0); free((char *)data->pack_objects_hook); } -- 2.29.2.533.g07db1f5344
