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[PATCH] Bluetooth: hci_event: fix OOB read and infinite loop in hci_le_create_big_complete_evt

hkbinbin posted 1 patch 1 day, 5 hours ago 
net/bluetooth/hci_event.c | 6 ++++++
1 file changed, 6 insertions(+)
[PATCH] Bluetooth: hci_event: fix OOB read and infinite loop in hci_le_create_big_complete_evt
Posted by hkbinbin 1 day, 5 hours ago 
hci_le_create_big_complete_evt() iterates over BT_BOUND connections
for a BIG handle using a while loop, accessing ev->bis_handle[i++]
on each iteration.  However, there is no check that i < ev->num_bis
before the array access.

When a controller sends a LE_Create_BIG_Complete event with num_bis=0
while BT_BOUND connections exist for that BIG handle, the loop reads
beyond the valid bis_handle[] entries into adjacent heap memory.
Since the out-of-bounds values typically exceed HCI_CONN_HANDLE_MAX
(0x0EFF), hci_conn_set_handle() rejects them and the connection
remains in BT_BOUND state.  The same connection is then found again
by hci_conn_hash_lookup_big_state(), creating an infinite loop with
hci_dev_lock held that blocks all Bluetooth operations:

  Bluetooth: hci0: Invalid handle: 0x6b6b > 0x0eff
  Bluetooth: hci0: Invalid handle: 0x6b6b > 0x0eff
  ... (repeats ~177 times)
  Bluetooth: hci0: Opcode 0x2040 failed: -110
  Bluetooth: hci0: command 0x2040 tx timeout

The value 0x6b6b is the KASAN slab free poison byte (0x6b),
confirming reads of freed/uninitialized heap memory.

Fix this by adding a bounds check on i against ev->num_bis before
accessing the array.  Connections beyond the reported count are
cleaned up with HCI_ERROR_UNSPECIFIED to prevent the infinite loop.

Fixes: a0bfde167b50 ("Bluetooth: ISO: Add support for connecting multiple BISes")
Cc: stable@vger.kernel.org
Signed-off-by: hkbinbin <hkbinbinbin@gmail.com>
---
 net/bluetooth/hci_event.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 286529d2e554..ebd7ae75b133 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -7085,6 +7085,12 @@ static void hci_le_create_big_complete_evt(struct hci_dev *hdev, void *data,
 			continue;
 		}
 
+		if (i >= ev->num_bis) {
+			hci_connect_cfm(conn, HCI_ERROR_UNSPECIFIED);
+			hci_conn_del(conn);
+			continue;
+		}
+
 		if (hci_conn_set_handle(conn,
 					__le16_to_cpu(ev->bis_handle[i++])))
 			continue;
-- 
2.51.0
Re: [PATCH] Bluetooth: hci_event: fix OOB read and infinite loop in hci_le_create_big_complete_evt
Posted by Luiz Augusto von Dentz 21 hours ago 
Hi Hkbinbin,

On Tue, Mar 31, 2026 at 1:50 AM hkbinbin <hkbinbinbin@gmail.com> wrote:
>
> hci_le_create_big_complete_evt() iterates over BT_BOUND connections
> for a BIG handle using a while loop, accessing ev->bis_handle[i++]
> on each iteration.  However, there is no check that i < ev->num_bis
> before the array access.
>
> When a controller sends a LE_Create_BIG_Complete event with num_bis=0
> while BT_BOUND connections exist for that BIG handle, the loop reads
> beyond the valid bis_handle[] entries into adjacent heap memory.
> Since the out-of-bounds values typically exceed HCI_CONN_HANDLE_MAX
> (0x0EFF), hci_conn_set_handle() rejects them and the connection
> remains in BT_BOUND state.  The same connection is then found again
> by hci_conn_hash_lookup_big_state(), creating an infinite loop with
> hci_dev_lock held that blocks all Bluetooth operations:
>
>   Bluetooth: hci0: Invalid handle: 0x6b6b > 0x0eff
>   Bluetooth: hci0: Invalid handle: 0x6b6b > 0x0eff
>   ... (repeats ~177 times)
>   Bluetooth: hci0: Opcode 0x2040 failed: -110
>   Bluetooth: hci0: command 0x2040 tx timeout
>
> The value 0x6b6b is the KASAN slab free poison byte (0x6b),
> confirming reads of freed/uninitialized heap memory.
>
> Fix this by adding a bounds check on i against ev->num_bis before
> accessing the array.  Connections beyond the reported count are
> cleaned up with HCI_ERROR_UNSPECIFIED to prevent the infinite loop.
>
> Fixes: a0bfde167b50 ("Bluetooth: ISO: Add support for connecting multiple BISes")
> Cc: stable@vger.kernel.org
> Signed-off-by: hkbinbin <hkbinbinbin@gmail.com>
> ---
>  net/bluetooth/hci_event.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
> index 286529d2e554..ebd7ae75b133 100644
> --- a/net/bluetooth/hci_event.c
> +++ b/net/bluetooth/hci_event.c
> @@ -7085,6 +7085,12 @@ static void hci_le_create_big_complete_evt(struct hci_dev *hdev, void *data,
>                         continue;
>                 }
>
> +               if (i >= ev->num_bis) {
> +                       hci_connect_cfm(conn, HCI_ERROR_UNSPECIFIED);
> +                       hci_conn_del(conn);
> +                       continue;
> +               }

https://sashiko.dev/#/patchset/20260331055032.1883139-1-hkbinbinbin%40gmail.com

Actually we might want to consider that all BISes failed if something
like this happens, so perhaps we should break and terminate if i !=
ev->num_bis


>                 if (hci_conn_set_handle(conn,
>                                         __le16_to_cpu(ev->bis_handle[i++])))
>                         continue;
> --
> 2.51.0
>


-- 
Luiz Augusto von Dentz
[PATCH v2] Bluetooth: hci_event: fix OOB read in hci_le_create_big_complete_evt
Posted by hkbinbin 20 hours ago 
hci_le_create_big_complete_evt() iterates over BT_BOUND connections for
a BIG handle using a while loop, accessing ev->bis_handle[i++] on each
iteration.  However, there is no check that i stays within ev->num_bis
before the array access.

When a controller sends a LE_Create_BIG_Complete event with fewer
bis_handle entries than there are BT_BOUND connections for that BIG,
or with num_bis=0, the loop reads beyond the valid bis_handle[] flex
array into adjacent heap memory.  Since the out-of-bounds values
typically exceed HCI_CONN_HANDLE_MAX (0x0EFF), hci_conn_set_handle()
rejects them and the connection remains in BT_BOUND state.  The same
connection is then found again by hci_conn_hash_lookup_big_state(),
creating an infinite loop with hci_dev_lock held.

Fix this by:

  - Breaking out of the loop when i reaches ev->num_bis and cleaning
    up all remaining BT_BOUND connections, then terminating the BIG
    since a mismatch between the host and controller state indicates
    failure.

  - Properly cleaning up the connection when hci_conn_set_handle()
    fails, instead of calling continue which leaves it in BT_BOUND
    state where it would be found again by the same lookup on the
    next iteration.

Fixes: a0bfde167b50 ("Bluetooth: ISO: Add support for connecting multiple BISes")
Cc: stable@vger.kernel.org
Signed-off-by: hkbinbin <hkbinbinbin@gmail.com>
---
 net/bluetooth/hci_event.c | 26 ++++++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 286529d2e554..64b5b497c491 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -7085,9 +7085,15 @@ static void hci_le_create_big_complete_evt(struct hci_dev *hdev, void *data,
 			continue;
 		}
 
+		if (i >= ev->num_bis)
+			break;
+
 		if (hci_conn_set_handle(conn,
-					__le16_to_cpu(ev->bis_handle[i++])))
+					__le16_to_cpu(ev->bis_handle[i++]))) {
+			hci_connect_cfm(conn, HCI_ERROR_UNSPECIFIED);
+			hci_conn_del(conn);
 			continue;
+		}
 
 		conn->state = BT_CONNECTED;
 		set_bit(HCI_CONN_BIG_CREATED, &conn->flags);
@@ -7096,7 +7102,22 @@ static void hci_le_create_big_complete_evt(struct hci_dev *hdev, void *data,
 		hci_iso_setup_path(conn);
 	}
 
-	if (!ev->status && !i)
+	if (conn) {
+		/* More bound connections than BIS handles reported by the
+		 * controller -- treat this as a failure for the entire BIG
+		 * and clean up any remaining BT_BOUND connections.
+		 */
+		do {
+			hci_connect_cfm(conn, HCI_ERROR_UNSPECIFIED);
+			hci_conn_del(conn);
+		} while ((conn = hci_conn_hash_lookup_big_state(hdev,
+							ev->handle,
+							BT_BOUND,
+							HCI_ROLE_MASTER)));
+
+		hci_cmd_sync_queue(hdev, hci_iso_term_big_sync,
+				   UINT_PTR(ev->handle), NULL);
+	} else if (!ev->status && !i) {
 		/* If no BISes have been connected for the BIG,
 		 * terminate. This is in case all bound connections
 		 * have been closed before the BIG creation
@@ -7104,6 +7125,7 @@ static void hci_le_create_big_complete_evt(struct hci_dev *hdev, void *data,
 		 */
 		hci_cmd_sync_queue(hdev, hci_iso_term_big_sync,
 				   UINT_PTR(ev->handle), NULL);
+	}
 
 	hci_dev_unlock(hdev);
 }
-- 
2.51.0
[PATCH v2] Bluetooth: hci_event: fix OOB read in hci_le_create_big_complete_evt
Posted by hkbinbin 20 hours ago 
hci_le_create_big_complete_evt() iterates over BT_BOUND connections for
a BIG handle using a while loop, accessing ev->bis_handle[i++] on each
iteration.  However, there is no check that i stays within ev->num_bis
before the array access.

When a controller sends a LE_Create_BIG_Complete event with fewer
bis_handle entries than there are BT_BOUND connections for that BIG,
or with num_bis=0, the loop reads beyond the valid bis_handle[] flex
array into adjacent heap memory.  Since the out-of-bounds values
typically exceed HCI_CONN_HANDLE_MAX (0x0EFF), hci_conn_set_handle()
rejects them and the connection remains in BT_BOUND state.  The same
connection is then found again by hci_conn_hash_lookup_big_state(),
creating an infinite loop with hci_dev_lock held.

Fix this by:

  - Breaking out of the loop when i reaches ev->num_bis and cleaning
    up all remaining BT_BOUND connections, then terminating the BIG
    since a mismatch between the host and controller state indicates
    failure.

  - Properly cleaning up the connection when hci_conn_set_handle()
    fails, instead of calling continue which leaves it in BT_BOUND
    state where it would be found again by the same lookup on the
    next iteration.

Fixes: a0bfde167b50 ("Bluetooth: ISO: Add support for connecting multiple BISes")
Cc: stable@vger.kernel.org
Signed-off-by: hkbinbin <hkbinbinbin@gmail.com>
---
 net/bluetooth/hci_event.c | 26 ++++++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 286529d2e554..64b5b497c491 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -7085,9 +7085,15 @@ static void hci_le_create_big_complete_evt(struct hci_dev *hdev, void *data,
 			continue;
 		}
 
+		if (i >= ev->num_bis)
+			break;
+
 		if (hci_conn_set_handle(conn,
-					__le16_to_cpu(ev->bis_handle[i++])))
+					__le16_to_cpu(ev->bis_handle[i++]))) {
+			hci_connect_cfm(conn, HCI_ERROR_UNSPECIFIED);
+			hci_conn_del(conn);
 			continue;
+		}
 
 		conn->state = BT_CONNECTED;
 		set_bit(HCI_CONN_BIG_CREATED, &conn->flags);
@@ -7096,7 +7102,22 @@ static void hci_le_create_big_complete_evt(struct hci_dev *hdev, void *data,
 		hci_iso_setup_path(conn);
 	}
 
-	if (!ev->status && !i)
+	if (conn) {
+		/* More bound connections than BIS handles reported by the
+		 * controller -- treat this as a failure for the entire BIG
+		 * and clean up any remaining BT_BOUND connections.
+		 */
+		do {
+			hci_connect_cfm(conn, HCI_ERROR_UNSPECIFIED);
+			hci_conn_del(conn);
+		} while ((conn = hci_conn_hash_lookup_big_state(hdev,
+							ev->handle,
+							BT_BOUND,
+							HCI_ROLE_MASTER)));
+
+		hci_cmd_sync_queue(hdev, hci_iso_term_big_sync,
+				   UINT_PTR(ev->handle), NULL);
+	} else if (!ev->status && !i) {
 		/* If no BISes have been connected for the BIG,
 		 * terminate. This is in case all bound connections
 		 * have been closed before the BIG creation
@@ -7104,6 +7125,7 @@ static void hci_le_create_big_complete_evt(struct hci_dev *hdev, void *data,
 		 */
 		hci_cmd_sync_queue(hdev, hci_iso_term_big_sync,
 				   UINT_PTR(ev->handle), NULL);
+	}
 
 	hci_dev_unlock(hdev);
 }
-- 
2.51.0

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