@matheusbsbs / matheus-bagliano / commits / 806278dead

commit-graph.c: handle corrupt/missing trees

Apply similar treatment as in the previous commit to handle an unchecked call to 'get_commit_tree_oid()'. Previously, a NULL return value from this function would be immediately dereferenced with '->hash', and then cause a segfault. Before dereferencing to access the 'hash' member, check the return value of 'get_commit_tree_oid()' to make sure that it is not NULL. To make this check correct, a related change is also needed in 'commit.c', which is to check the return value of 'get_commit_tree' before taking its address. If 'get_commit_tree' returns NULL, we encounter an undefined behavior when taking the address of the return value of 'get_commit_tree' and then taking '->object.oid'. (On my system, this is memory address 0x8, which is obviously wrong). Fix this by making sure that 'get_commit_tree' returns something non-NULL before digging through a structure that is not there, thus preventing a segfault down the line in the commit graph code. Signed-off-by: Taylor Blau <me@ttaylorr.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Taylor Blau committed Sep 5, 2019 at 18:04 UTC 806278dead57766bf000af62dcb8892ee3a24956

3 files changed +9 -3

commit-graph.c

+6 -1

@@ -839,6 +839,7 @@ static void write_graph_chunk_data(struct hashfile *f, int hash_len,

839

840 while (list < last) {

841 struct commit_list *parent;

842 + struct object_id *tree;

843 int edge_value;

844 uint32_t packedDate[2];

845 display_progress(ctx->progress, ++ctx->progress_cnt);

@@ -846,7 +847,11 @@ static void write_graph_chunk_data(struct hashfile *f, int hash_len,

847 if (parse_commit_no_graph(*list))

848 die(_("unable to parse commit %s"),

849 oid_to_hex(&(*list)->object.oid));

849 - hashwrite(f, get_commit_tree_oid(*list)->hash, hash_len);

850 + tree = get_commit_tree_oid(*list);

851 + if (!tree)

852 + die(_("unable to get tree for %s"),

853 + oid_to_hex(&(*list)->object.oid));

854 + hashwrite(f, tree->hash, hash_len);

855

856 parent = (*list)->parents;

857

commit.c

+2 -1

@@ -358,7 +358,8 @@ struct tree *repo_get_commit_tree(struct repository *r,

358

359 struct object_id *get_commit_tree_oid(const struct commit *commit)

360 {

361 - return &get_commit_tree(commit)->object.oid;

361 + struct tree *tree = get_commit_tree(commit);

362 + return tree ? &tree->object.oid : NULL;

363 }

364

365 void release_commit_memory(struct parsed_object_pool *pool, struct commit *c)

t/t5318-commit-graph.sh

+1 -1

@@ -607,7 +607,7 @@ test_expect_success 'corrupt commit-graph write (broken parent)' '

607 )

608 '

609

610 -test_expect_failure 'corrupt commit-graph write (missing tree)' '

610 +test_expect_success 'corrupt commit-graph write (missing tree)' '

611 rm -rf repo &&

612 git init repo &&

613 (