Merge branch 'ps/upload-pack-oom-protection' into maint-2.51

A broken or malicious "git fetch" can say that it has the same
object for many many times, and the upload-pack serving it can
exhaust memory storing them redundantly, which has been corrected.

* ps/upload-pack-oom-protection:
  upload-pack: don't ACK non-commits repeatedly in protocol v2
  t5530: modernize tests

t/t5530-upload-pack-error.sh

@@ -4,8 +4,6 @@ test_description='errors in upload-pack'
 
 . ./test-lib.sh
 
-D=$(pwd)
-
 corrupt_repo () {
 	object_sha1=$(git rev-parse "$1") &&
 	ob=$(expr "$object_sha1" : "\(..\)") &&
@@ -21,11 +19,7 @@ test_expect_success 'setup and corrupt repository' '
 	test_tick &&
 	echo changed >file &&
 	git commit -a -m changed &&
-	corrupt_repo HEAD:file
+	corrupt_repo HEAD:file &&
-
-'
-
-test_expect_success 'fsck fails' '
 	test_must_fail git fsck
 '
 
@@ -40,17 +34,12 @@ test_expect_success 'upload-pack fails due to error in pack-objects packing' '
 '
 
 test_expect_success 'corrupt repo differently' '
-
 	git hash-object -w file &&
-	corrupt_repo HEAD^^{tree}
+	corrupt_repo HEAD^^{tree} &&
-
-'
-
-test_expect_success 'fsck fails' '
 	test_must_fail git fsck
 '
-test_expect_success 'upload-pack fails due to error in rev-list' '
 
+test_expect_success 'upload-pack fails due to error in rev-list' '
 	printf "%04xwant %s\n%04xshallow %s00000009done\n0000" \
 		$(($hexsz + 10)) $(git rev-parse HEAD) \
 		$(($hexsz + 12)) $(git rev-parse HEAD^) >input &&
@@ -59,7 +48,6 @@ test_expect_success 'upload-pack fails due to error in rev-list' '
 '
 
 test_expect_success 'upload-pack fails due to bad want (no object)' '
-
 	printf "%04xwant %s multi_ack_detailed\n00000009done\n0000" \
 		$(($hexsz + 29)) $(test_oid deadbeef) >input &&
 	test_must_fail git upload-pack . <input >output 2>output.err &&
@@ -69,7 +57,6 @@ test_expect_success 'upload-pack fails due to bad want (no object)' '
 '
 
 test_expect_success 'upload-pack fails due to bad want (not tip)' '
-
 	oid=$(echo an object we have | git hash-object -w --stdin) &&
 	printf "%04xwant %s multi_ack_detailed\n00000009done\n0000" \
 		$(($hexsz + 29)) "$oid" >input &&
@@ -80,7 +67,6 @@ test_expect_success 'upload-pack fails due to bad want (not tip)' '
 '
 
 test_expect_success 'upload-pack fails due to error in pack-objects enumeration' '
-
 	printf "%04xwant %s\n00000009done\n0000" \
 		$((hexsz + 10)) $(git rev-parse HEAD) >input &&
 	test_must_fail git upload-pack . <input >/dev/null 2>output.err &&
@@ -105,18 +91,48 @@ test_expect_success 'upload-pack tolerates EOF just after stateless client wants
 	test_cmp expect actual
 '
 
-test_expect_success 'create empty repository' '
+test_expect_success 'fetch fails' '
-
+	git init foo &&
-	mkdir foo &&
+	test_must_fail git -C foo fetch .. main
-	cd foo &&
-	git init
-
 '
 
-test_expect_success 'fetch fails' '
+test_expect_success 'upload-pack ACKs repeated non-commit objects repeatedly (protocol v0)' '
-
+	commit_id=$(git rev-parse HEAD) &&
-	test_must_fail git fetch .. main
+	tree_id=$(git rev-parse HEAD^{tree}) &&
+	test-tool pkt-line pack >request <<-EOF &&
+	want $commit_id
+	0000
+	have $tree_id
+	have $tree_id
+	0000
+	EOF
+	git upload-pack --stateless-rpc . <request >actual &&
+	depacketize <actual >actual.raw &&
+	grep ^ACK actual.raw >actual.acks &&
+	cat >expect <<-EOF &&
+	ACK $tree_id
+	ACK $tree_id
+	EOF
+	test_cmp expect actual.acks
+'
 
+test_expect_success 'upload-pack ACKs repeated non-commit objects once only (protocol v2)' '
+	commit_id=$(git rev-parse HEAD) &&
+	tree_id=$(git rev-parse HEAD^{tree}) &&
+	test-tool pkt-line pack >request <<-EOF &&
+	command=fetch
+	object-format=$(test_oid algo)
+	0001
+	want $commit_id
+	have $tree_id
+	have $tree_id
+	0000
+	EOF
+	GIT_PROTOCOL=version=2 git upload-pack . <request >actual &&
+	depacketize <actual >actual.raw &&
+	grep ^ACK actual.raw >actual.acks &&
+	echo "ACK $tree_id" >expect &&
+	test_cmp expect actual.acks
 '
 
 test_done

upload-pack.c

@@ -476,20 +476,17 @@ static void create_pack_file(struct upload_pack_data *pack_data,
 
 static int do_got_oid(struct upload_pack_data *data, const struct object_id *oid)
 {
-	int we_knew_they_have = 0;
 	struct object *o = parse_object_with_flags(the_repository, oid,
 						   PARSE_OBJECT_SKIP_HASH_CHECK |
 						   PARSE_OBJECT_DISCARD_TREE);
 
 	if (!o)
 		die("oops (%s)", oid_to_hex(oid));
+
 	if (o->type == OBJ_COMMIT) {
 		struct commit_list *parents;
 		struct commit *commit = (struct commit *)o;
-		if (o->flags & THEY_HAVE)
+
-			we_knew_they_have = 1;
-		else
-			o->flags |= THEY_HAVE;
 		if (!data->oldest_have || (commit->date < data->oldest_have))
 			data->oldest_have = commit->date;
 		for (parents = commit->parents;
@@ -497,11 +494,13 @@ static int do_got_oid(struct upload_pack_data *data, const struct object_id *oid
 		     parents = parents->next)
 			parents->item->object.flags |= THEY_HAVE;
 	}
-	if (!we_knew_they_have) {
+
-		add_object_array(o, NULL, &data->have_obj);
+	if (o->flags & THEY_HAVE)
-		return 1;
+		return 0;
-	}
+	o->flags |= THEY_HAVE;
-	return 0;
+
+	add_object_array(o, NULL, &data->have_obj);
+	return 1;
 }
 
 static int got_oid(struct upload_pack_data *data,