Deadlock when marking as read message in a search folder

There could happen a deadlock when two threads change for example
message info flags, where one threads holds message info's summary lock
and is waiting for the info's property lock, which the other thread
hold's info's property lock and is waiting for the summary lock.
It's safer to hold summary lock before acquiring the message info's
lock when anything will be changed in the message info, which didn't
happen here.

This had been reported downstream at:
https://bugzilla.redhat.com/show_bug.cgi?id=1649373

2 files changed, 43 insertions, 5 deletions

diff --git a/src/camel/camel-folder.c b/src/camel/camel-folder.c
index abece0c9f..c017bc365 100644
--- a/src/camel/camel-folder.c
+++ b/src/camel/camel-folder.c
@@ -285,25 +285,41 @@ folder_filter (CamelSession *session,
 
 	/* Reset junk learn flag so that we don't process it again */
 	if (data->junk) {
+		CamelFolderSummary *summary;
+
+		summary = camel_folder_get_folder_summary (data->folder);
+
+		camel_folder_summary_lock (summary);
+
 		for (i = 0; i < data->junk->len; i++) {
-			info = camel_folder_summary_get (camel_folder_get_folder_summary (data->folder), data->junk->pdata[i]);
+			info = camel_folder_summary_get (summary, data->junk->pdata[i]);
 			if (!info)
 				continue;
 
 			camel_message_info_set_flags (info, CAMEL_MESSAGE_JUNK_LEARN, 0);
 			g_clear_object (&info);
 		}
+
+		camel_folder_summary_unlock (summary);
 	}
 
 	if (data->notjunk) {
+		CamelFolderSummary *summary;
+
+		summary = camel_folder_get_folder_summary (data->folder);
+
+		camel_folder_summary_lock (summary);
+
 		for (i = 0; i < data->notjunk->len; i++) {
-			info = camel_folder_summary_get (camel_folder_get_folder_summary (data->folder), data->notjunk->pdata[i]);
+			info = camel_folder_summary_get (summary, data->notjunk->pdata[i]);
 			if (!info)
 				continue;
 
 			camel_message_info_set_flags (info, CAMEL_MESSAGE_JUNK_LEARN, 0);
 			g_clear_object (&info);
 		}
+
+		camel_folder_summary_unlock (summary);
 	}
 
 	if (data->junk) {
@@ -749,13 +765,19 @@ folder_set_message_flags (CamelFolder *folder,
 
 	g_return_val_if_fail (folder->priv->summary != NULL, FALSE);
 
+	camel_folder_summary_lock (folder->priv->summary);
+
 	info = camel_folder_summary_get (folder->priv->summary, uid);
-	if (info == NULL)
+	if (info == NULL) {
+		camel_folder_summary_unlock (folder->priv->summary);
 		return FALSE;
+	}
 
 	res = camel_message_info_set_flags (info, mask, set);
 	g_clear_object (&info);
 
+	camel_folder_summary_unlock (folder->priv->summary);
+
 	return res;
 }
 
@@ -789,12 +811,18 @@ folder_set_message_user_flag (CamelFolder *folder,
 
 	g_return_if_fail (folder->priv->summary != NULL);
 
+	camel_folder_summary_lock (folder->priv->summary);
+
 	info = camel_folder_summary_get (folder->priv->summary, uid);
-	if (info == NULL)
+	if (info == NULL) {
+		camel_folder_summary_unlock (folder->priv->summary);
 		return;
+	}
 
 	camel_message_info_set_user_flag (info, name, value);
 	g_clear_object (&info);
+
+	camel_folder_summary_unlock (folder->priv->summary);
 }
 
 static const gchar *
@@ -827,12 +855,18 @@ folder_set_message_user_tag (CamelFolder *folder,
 
 	g_return_if_fail (folder->priv->summary != NULL);
 
+	camel_folder_summary_lock (folder->priv->summary);
+
 	info = camel_folder_summary_get (folder->priv->summary, uid);
-	if (info == NULL)
+	if (info == NULL) {
+		camel_folder_summary_unlock (folder->priv->summary);
 		return;
+	}
 
 	camel_message_info_set_user_tag (info, name, value);
 	g_clear_object (&info);
+
+	camel_folder_summary_unlock (folder->priv->summary);
 }
 
 static GPtrArray *
diff --git a/src/camel/camel-vee-folder.c b/src/camel/camel-vee-folder.c
index aae394c7c..383e92385 100644
--- a/src/camel/camel-vee-folder.c
+++ b/src/camel/camel-vee-folder.c
@@ -139,6 +139,8 @@ vee_folder_note_added_uid (CamelVeeFolder *vfolder,
 {
 	const gchar *vuid;
 
+	camel_folder_summary_lock (CAMEL_FOLDER_SUMMARY (vsummary));
+
 	vuid = camel_vee_message_info_data_get_vee_message_uid (added_mi_data);
 	if (!camel_folder_summary_check_uid (CAMEL_FOLDER_SUMMARY (vsummary), vuid)) {
 		/* add it only if it wasn't in yet */
@@ -158,6 +160,8 @@ vee_folder_note_added_uid (CamelVeeFolder *vfolder,
 		if (included_as_changed && changes)
 			camel_folder_change_info_change_uid (changes, vuid);
 	}
+
+	camel_folder_summary_unlock (CAMEL_FOLDER_SUMMARY (vsummary));
 }
 
 static void