Re: [PATCH BlueZ] media: fix crash when clearing BAP transport
From: Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Date: 2023-02-13 22:08:58
Hi Pauli, On Mon, Feb 13, 2023 at 1:28 PM Pauli Virtanen [off-list ref] wrote:
The BAP stream user data used for transport paths in media.c is set both in media.c:pac_config and in profiles/bap.c. In the latter, it gets set to a string owned by bap_ep, whose lifetime can be shorter than that of the transport. Under some conditions, bap.c:bap_disconnect is hit while there are transports and the user data is owned by the endpoint. In this case, the path string owned by the endpoints gets freed first, and ASAN use-after-free crash is encountered when clearing the transports.
Hmm, I didn't hit while testing, anyway that means the transport is being freed before we clean up? It might be a good idea to run this under valgrind to check where the path is freed.
quoted hunk ↗ jump to hunk
Fix this by matching the transports by the stream pointer, and not by the transport/endpoint path. Fixes: 7b1b1a499cf3 ("media: clear the right transport when clearing BAP endpoint") --- Notes: The v2 version of the patch in commit 7b1b1a499cf334 was buggy, and its v3 sent to the list was supposed to replace it. However, I resubmitted only that patch and not the full series, which maybe would have been the right thing. Sorry for the mess. profiles/audio/media.c | 21 +++++++++++---------- profiles/audio/transport.c | 14 ++++++++++++++ profiles/audio/transport.h | 1 + 3 files changed, 26 insertions(+), 10 deletions(-)diff --git a/profiles/audio/media.c b/profiles/audio/media.c index 3eb038cb7..8728b69e0 100644 --- a/profiles/audio/media.c +++ b/profiles/audio/media.c@@ -1085,19 +1085,20 @@ static int pac_config(struct bt_bap_stream *stream, struct iovec *cfg, static void pac_clear(struct bt_bap_stream *stream, void *user_data) { struct media_endpoint *endpoint = user_data; - struct media_transport *transport; - const char *path; + GSList *item; - path = bt_bap_stream_get_user_data(stream); - if (!path) - return; + DBG("endpoint %p stream %p", endpoint, stream); - DBG("endpoint %p path %s", endpoint, path); + item = endpoint->transports; + while (item) { + struct media_transport *transport = item->data; - transport = find_transport(endpoint, path); - if (transport) { - clear_configuration(endpoint, transport); - bt_bap_stream_set_user_data(stream, NULL); + if (media_transport_get_stream(transport) == stream) { + clear_configuration(endpoint, transport); + item = endpoint->transports; + } else { + item = item->next; + } } }diff --git a/profiles/audio/transport.c b/profiles/audio/transport.c index 5e057e2a5..cd91669c6 100644 --- a/profiles/audio/transport.c +++ b/profiles/audio/transport.c@@ -1483,6 +1483,20 @@ const char *media_transport_get_path(struct media_transport *transport) return transport->path; } +void *media_transport_get_stream(struct media_transport *transport) +{ + struct bap_transport *bap; + const char *uuid; + + uuid = media_endpoint_get_uuid(transport->endpoint); + if (strcasecmp(uuid, PAC_SINK_UUID) && + strcasecmp(uuid, PAC_SOURCE_UUID)) + return NULL;
This should probably be made generic, perhaps with a get_stream callback so we don't have to check the UUID like above.
quoted hunk ↗ jump to hunk
+ + bap = transport->data; + return bap->stream; +} + void media_transport_update_delay(struct media_transport *transport, uint16_t delay) {diff --git a/profiles/audio/transport.h b/profiles/audio/transport.h index 102fc3cf1..5ca9b8f9e 100644 --- a/profiles/audio/transport.h +++ b/profiles/audio/transport.h@@ -19,6 +19,7 @@ struct media_transport *media_transport_create(struct btd_device *device, void media_transport_destroy(struct media_transport *transport); const char *media_transport_get_path(struct media_transport *transport); +void *media_transport_get_stream(struct media_transport *transport); struct btd_device *media_transport_get_dev(struct media_transport *transport); int8_t media_transport_get_volume(struct media_transport *transport); void media_transport_update_delay(struct media_transport *transport, --2.39.1
-- Luiz Augusto von Dentz