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From:   Luiz Augusto von Dentz <luiz.dentz@gmail.com>
To:     linux-bluetooth@vger.kernel.org
Subject: [PATCH BlueZ 5/6] shared/bap: Fix crash when canceling requests
Date:   Mon, 14 Nov 2022 16:30:37 -0800
Message-Id: <20221115003038.2134340-5-luiz.dentz@gmail.com>
In-Reply-To: <20221115003038.2134340-1-luiz.dentz@gmail.com>
References: <20221115003038.2134340-1-luiz.dentz@gmail.com>
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From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

If bt_bap_unref/bap_free is called while there is an ongoing pending
request it may endup calling into bap_notify_ready which will try to
notify ready callbacks while holding a reference, but in case the
reference is already 0 that means it would switch to 1 and back 0
causing a double free.

To prevent that bap_notify_ready now checks that the reference is not 0
with use of bt_bap_ref_safe.
---
 src/shared/bap.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/src/shared/bap.c b/src/shared/bap.c
index 25369e619051..21aa8aa6c5ca 100644
--- a/src/shared/bap.c
+++ b/src/shared/bap.c
@@ -2638,6 +2638,14 @@ struct bt_bap *bt_bap_ref(struct bt_bap *bap)
 	return bap;
 }
 
+static struct bt_bap *bt_bap_ref_safe(struct bt_bap *bap)
+{
+	if (!bap || !bap->ref_count)
+		return NULL;
+
+	return bt_bap_ref(bap);
+}
+
 void bt_bap_unref(struct bt_bap *bap)
 {
 	if (!bap)
@@ -2656,7 +2664,8 @@ static void bap_notify_ready(struct bt_bap *bap)
 	if (!queue_isempty(bap->pending))
 		return;
 
-	bt_bap_ref(bap);
+	if (!bt_bap_ref_safe(bap))
+		return;
 
 	for (entry = queue_get_entries(bap->ready_cbs); entry;
 							entry = entry->next) {
-- 
2.37.3