[PATCH 6.6 067/175] Bluetooth: btusb: clamp SCO altsetting table indices

Greg Kroah-Hartman
2026-03-31T16:26:32Z

From: Pengpeng Hou <pengpeng@iscas.ac.cn>

[ Upstream commit 129fa608b6ad08b8ab7178eeb2ec272c993aaccc ]

btusb_work() maps the number of active SCO links to USB alternate
settings through a three-entry lookup table when CVSD traffic uses
transparent voice settings. The lookup currently indexes alts[] with
data->sco_num - 1 without first constraining sco_num to the number of
available table entries.

While the table only defines alternate settings for up to three SCO
links, data->sco_num comes from hci_conn_num() and is used directly.
Cap the lookup to the last table entry before indexing it so the
driver keeps selecting the highest supported alternate setting without
reading past alts[].

Fixes: baac6276c0a9 ("Bluetooth: btusb: handle mSBC audio over USB Endpoints")
Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/bluetooth/btusb.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
index 168e46ce59976..c51523d780e65 100644
--- a/drivers/bluetooth/btusb.c
+++ b/drivers/bluetooth/btusb.c
@@ -2314,8 +2314,11 @@ static void btusb_work(struct work_struct *work)
if (data->air_mode == HCI_NOTIFY_ENABLE_SCO_CVSD) {
if (hdev->voice_setting & 0x0020) {
static const int alts[3] = { 2, 4, 5 };
+ unsigned int sco_idx;

- new_alts = alts[data->sco_num - 1];
+ sco_idx = min_t(unsigned int, data->sco_num - 1,
+ ARRAY_SIZE(alts) - 1);
+ new_alts = alts[sco_idx];
} else {
new_alts = data->sco_num;
}
--
2.51.0