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163 lines
7.2 KiB
163 lines
7.2 KiB
4 years ago
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From 1b5282d8303177cebf8496656da1dada29517e9d Mon Sep 17 00:00:00 2001
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From: Debarshi Ray <debarshir@freedesktop.org>
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Date: Fri, 4 Dec 2020 02:17:48 +0100
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Subject: [PATCH] Don't remove a queue more than once
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Currently, the dleyna_task_processor_remove_queues_for_sink and
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dleyna_task_processor_remove_queues_for_source APIs can corrupt the
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memory of the hash table of queues in the processor.
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These APIs iterate through the queues in the hash table using
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g_hash_table_foreach_remove, and let the callbacks return TRUE when a
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queue is to be removed. Unfortunately, the callbacks use prv_cancel,
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which might have already removed the queue using g_hash_table_remove.
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It happens specifically for queues that have no current_task and have
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the DLEYNA_TASK_QUEUE_FLAG_AUTO_REMOVE flag set.
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dleyna-renderer-service has such a queue, whose task_delete_cb handler
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is set to dleyna_gasync_task_delete_cb. When dleyna-renderer-service
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loses it's last D-Bus client, it first invokes
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dleyna_task_processor_remove_queues_for_source, followed by
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dleyna_task_processor_set_quitting. The former corrupts the hash
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table. The latter invokes prv_cancel_all_queues, which again goes
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through the hash table and tries to remove them. This leads to crashes
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with backtraces containing dleyna_gasync_task_delete_cb, GPtrArray,
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prv_task_cancel_and_free_cb, or similar code paths originating from
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prv_cancel_only.
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Here's an example:
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%0 prv_task_cancel_and_free_cb (data=0x56246f2425f0,
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user_data=<optimized out>)
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at libdleyna/core/task-processor.c:180
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%1 g_ptr_array_foreach (array=0x56246f68b5a0,
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func=0x7f41d2335850 <prv_task_cancel_and_free_cb>,
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user_data=0x56246f4ea1a0)
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at ../glib/garray.c:2091
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%2 prv_cancel_only (queue_id=<optimized out>,
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task_queue=0x56246f4ea1a0)
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at libdleyna/core/task-processor.c:193
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%3 prv_cancel_cb (key=<optimized out>,
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value=0x56246f4ea1a0,
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user_data=<optimized out>)
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at libdleyna/core/task-processor.c:229
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%4 g_hash_table_foreach_remove_or_steal (hash_table=0x56246f1e82a0,
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func=func@entry=0x7f41d2335c10 <prv_cancel_cb>,
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user_data=user_data@entry=0x0,
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notify=notify@entry=1)
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at ../glib/ghash.c:1947
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%5 g_hash_table_foreach_remove (hash_table=<optimized out>,
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func=func@entry=0x7f41d2335c10 <prv_cancel_cb>,
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user_data=user_data@entry=0x0)
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at ../glib/ghash.c:1993
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%6 prv_cancel_all_queues (processor=0x56246f1f3510)
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at libdleyna/core/task-processor.c:244
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%7 dleyna_task_processor_set_quitting (processor=0x56246f1f3510)
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at libdleyna/core/task-processor.c:259
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%8 prv_lost_client (connection=<optimized out>,
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name=0x56246f24e5d0 ":1.47515",
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user_data=<optimized out>)
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at src/connector-dbus.c:283
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%9 actually_do_call (call_type=CALL_TYPE_NAME_VANISHED,
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name_owner=<optimized out>,
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connection=<optimized out>,
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client=0x56246f24efb0)
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at ../gio/gdbusnamewatching.c:171
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%10 actually_do_call (call_type=CALL_TYPE_NAME_VANISHED,
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name_owner=<optimized out>,
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connection=<optimized out>,
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client=0x56246f24efb0)
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at ../gio/gdbusnamewatching.c:149
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%11 do_call (client=0x56246f24efb0, call_type=CALL_TYPE_NAME_VANISHED)
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at ../gio/gdbusnamewatching.c:224
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%12 call_vanished_handler (client=0x56246f24efb0)
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at ../gio/gdbusnamewatching.c:249
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%13 call_vanished_handler (client=0x56246f24efb0)
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at ../gio/gdbusnamewatching.c:242
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%14 on_name_owner_changed (connection=<optimized out>,
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sender_name=0x56246f24a260 "org.freedesktop.DBus",
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object_path=0x56246f7ad950 "/org/freedesktop/DBus",
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interface_name=0x56246f27a2a0 "org.freedesktop.DBus",
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signal_name=<optimized out>,
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parameters=0x56246f21ee90, user_data=0x1)
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at ../gio/gdbusnamewatching.c:352
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%15 emit_signal_instance_in_idle_cb (data=data@entry=0x56246f236950)
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at ../gio/gdbusconnection.c:3777
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%16 g_idle_dispatch (source=source@entry=0x56246f7080a0,
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callback=0x7f41d1e1e640 <emit_signal_instance_in_idle_cb>,
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user_data=0x56246f236950)
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at ../glib/gmain.c:5836
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%17 g_main_dispatch (context=0x56246f1f2920) at ../glib/gmain.c:3325
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%18 g_main_context_dispatch (context=0x56246f1f2920)
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at ../glib/gmain.c:4043
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%19 g_main_context_iterate.constprop.0 (context=0x56246f1f2920,
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block=block@entry=1,
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dispatch=dispatch@entry=1,
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self=<optimized out>)
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at ../glib/gmain.c:4119
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%20 g_main_loop_run (loop=0x56246f2337a0) at ../glib/gmain.c:4317
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%21 dleyna_main_loop_start (server=<optimized out>,
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control_point=<optimized out>,
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user_data=<optimized out>)
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at libdleyna/core/main-loop.c:154
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%22 __libc_start_main (main=0x56246d8b40d0 <main>,
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argc=1,
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argv=0x7ffd4b757768,
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init=<optimized out>,
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fini=<optimized out>,
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rtld_fini=<optimized out>,
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stack_end=0x7ffd4b757758)
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at ../csu/libc-start.c:314
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%23 _start ()
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Looking at the innards of the task_queue, it's seen that all the
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function pointers have the same value, which doesn't match with the
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reality of the code and is indicative of a memory error:
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(gdb) print *task_queue
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$2 = {tasks = 0x56210d62385a,
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task_process_cb = 0x9595959595959595,
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task_cancel_cb = 0x9595959595959595,
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task_delete_cb = 0x9595959595959595,
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task_queue_finally_cb = 0x9595959595959595,
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current_task = 0x9595959595959595,
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idle_id = 2509608341,
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defer_remove = -1785358955,
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flags = 2509608341,
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user_data = 0x9595959595959595,
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cancelled = -1785358955}
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Based on initial work done by Robert Tiemann.
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https://bugzilla.redhat.com/show_bug.cgi?id=1903139
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https://github.com/phako/dleyna-core/pull/1
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---
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libdleyna/core/task-processor.c | 4 ++--
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1 file changed, 2 insertions(+), 2 deletions(-)
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diff --git a/libdleyna/core/task-processor.c b/libdleyna/core/task-processor.c
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index 39529a3dc967..f50dd569ed61 100644
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--- a/libdleyna/core/task-processor.c
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+++ b/libdleyna/core/task-processor.c
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@@ -285,7 +285,7 @@ static gboolean prv_free_queue_for_source(gpointer key, gpointer value,
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if (!strcmp(source, queue_key->source) && !queue->defer_remove) {
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queue->defer_remove = (queue->current_task != NULL);
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- prv_cancel(queue_key, queue);
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+ prv_cancel_only(queue_key, queue);
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if (!queue->defer_remove) {
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DLEYNA_LOG_DEBUG("Removing queue <%s,%s>",
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@@ -320,7 +320,7 @@ static gboolean prv_free_queue_for_sink(gpointer key, gpointer value,
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if (!strcmp(sink, queue_key->sink) && !queue->defer_remove) {
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queue->defer_remove = (queue->current_task != NULL);
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- prv_cancel(queue_key, queue);
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+ prv_cancel_only(queue_key, queue);
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if (!queue->defer_remove) {
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DLEYNA_LOG_DEBUG("Removing queue <%s,%s>",
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--
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2.28.0
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