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Always check parse_tree*()'s return value

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Otherwise we may easily run into serious crashes: For example, if we run
`init_tree_desc()` directly after a failed `parse_tree()`, we are
accessing uninitialized data or trying to dereference `NULL`.

Note that the `parse_tree()` function already takes care of showing an
error message. The `parse_tree_indirectly()` and
`repo_get_commit_tree()` functions do not, therefore those latter call
sites need to show a useful error message while the former do not.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Johannes Schindelin
2024-02-23 08:34:23 +00:00
committed by Junio C Hamano
parent 98c6d16d67
commit aa9f618909
12 changed files with 52 additions and 10 deletions
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19
builtin/checkout.c
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@@ -707,7 +707,8 @@ static int reset_tree(struct tree *tree, const struct checkout_opts *o,
init_checkout_metadata(&opts.meta, info->refname,
info->commit ? &info->commit->object.oid : null_oid(),
NULL);
parse_tree(tree);
if (parse_tree(tree) < 0)
return 128;
init_tree_desc(&tree_desc, tree->buffer, tree->size);
switch (unpack_trees(1, &tree_desc, &opts)) {
case -2:
@@ -786,9 +787,15 @@ static int merge_working_tree(const struct checkout_opts *opts,
if (new_branch_info->commit)
BUG("'switch --orphan' should never accept a commit as starting point");
new_tree = parse_tree_indirect(the_hash_algo->empty_tree);
} else
if (!new_tree)
BUG("unable to read empty tree");
} else {
new_tree = repo_get_commit_tree(the_repository,
new_branch_info->commit);
if (!new_tree)
return error(_("unable to read tree (%s)"),
oid_to_hex(&new_branch_info->commit->object.oid));
}
if (opts->discard_changes) {
ret = reset_tree(new_tree, opts, 1, writeout_error, new_branch_info);
if (ret)
@@ -823,7 +830,8 @@ static int merge_working_tree(const struct checkout_opts *opts,
oid_to_hex(old_commit_oid));
init_tree_desc(&trees[0], tree->buffer, tree->size);
parse_tree(new_tree);
if (parse_tree(new_tree) < 0)
exit(128);
tree = new_tree;
init_tree_desc(&trees[1], tree->buffer, tree->size);
@@ -1239,10 +1247,15 @@ static void setup_new_branch_info_and_source_tree(
if (!new_branch_info->commit) {
/* not a commit */
*source_tree = parse_tree_indirect(rev);
if (!*source_tree)
die(_("unable to read tree (%s)"), oid_to_hex(rev));
} else {
parse_commit_or_die(new_branch_info->commit);
*source_tree = repo_get_commit_tree(the_repository,
new_branch_info->commit);
if (!*source_tree)
die(_("unable to read tree (%s)"),
oid_to_hex(&new_branch_info->commit->object.oid));
}
}