From 393c13b940be8f2e5b126cd9f442c12e7ecb4cac Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Thu, 27 Jul 2017 16:47:08 +0200 Subject: [PATCH] bt: stop the sdp memory allocation craziness Clang static analyzer reports a memory leak. Actually, the allocated memory escapes here: record->attribute_list[record->attributes].pair = data; but clang is correct that the memory might leak if len is zero. We know it isn't; assert that it is the case. The craziness doesn't end there. The memory is freed by bt_l2cap_sdp_close_ch: g_free(sdp->service_list[i].attribute_list->pair); which actually should have been written like this: g_free(sdp->service_list[i].attribute_list[0].pair); The attribute_list is sorted with qsort; but indeed the first entry of attribute_list should point to "data" even after the qsort, because the first record has id SDP_ATTR_RECORD_HANDLE, whose numeric value is zero. But hang on. The qsort function is static int sdp_attributeid_compare( const struct sdp_service_attribute_s *a, const struct sdp_service_attribute_s *b) { return (int) b->attribute_id - a->attribute_id; } but no one ever writes attribute_id. So it only works if qsort is stable, and who knows what else is broken, but we can fix it by setting attribute_id in the while loop. Signed-off-by: Paolo Bonzini --- hw/bt/sdp.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/hw/bt/sdp.c b/hw/bt/sdp.c index f67b3b89c0..3cb60b9495 100644 --- a/hw/bt/sdp.c +++ b/hw/bt/sdp.c @@ -580,7 +580,7 @@ static void bt_l2cap_sdp_close_ch(void *opaque) int i; for (i = 0; i < sdp->services; i ++) { - g_free(sdp->service_list[i].attribute_list->pair); + g_free(sdp->service_list[i].attribute_list[0].pair); g_free(sdp->service_list[i].attribute_list); g_free(sdp->service_list[i].uuid); } @@ -720,6 +720,8 @@ static void sdp_service_record_build(struct sdp_service_record_s *record, len += sdp_attr_max_size(&def->attributes[record->attributes ++].data, &record->uuids); } + + assert(len > 0); record->uuids = pow2ceil(record->uuids); record->attribute_list = g_malloc0(record->attributes * sizeof(*record->attribute_list)); @@ -730,12 +732,14 @@ static void sdp_service_record_build(struct sdp_service_record_s *record, record->attributes = 0; uuid = record->uuid; while (def->attributes[record->attributes].data.type) { + int attribute_id = def->attributes[record->attributes].id; record->attribute_list[record->attributes].pair = data; + record->attribute_list[record->attributes].attribute_id = attribute_id; len = 0; data[len ++] = SDP_DTYPE_UINT | SDP_DSIZE_2; - data[len ++] = def->attributes[record->attributes].id >> 8; - data[len ++] = def->attributes[record->attributes].id & 0xff; + data[len ++] = attribute_id >> 8; + data[len ++] = attribute_id & 0xff; len += sdp_attr_write(data + len, &def->attributes[record->attributes].data, &uuid); @@ -749,10 +753,15 @@ static void sdp_service_record_build(struct sdp_service_record_s *record, data += len; } - /* Sort the attribute list by the AttributeID */ + /* Sort the attribute list by the AttributeID. The first must be + * SDP_ATTR_RECORD_HANDLE so that bt_l2cap_sdp_close_ch can free + * the buffer. + */ qsort(record->attribute_list, record->attributes, sizeof(*record->attribute_list), (void *) sdp_attributeid_compare); + assert(record->attribute_list[0].pair == data); + /* Sort the searchable UUIDs list for bisection */ qsort(record->uuid, record->uuids, sizeof(*record->uuid), -- 2.39.2