FROMLIST: Bluetooth: Tolerate valid pre 4.2 conn params
This patch tolerates connection parameters that were valid before
ESR08_v1.0.0 which was also incoporated into the 4.2 core specification.
In particular, this addresses compatibility issues with the Lenovo Yoga
Mouse that sees its connection parameters rejected by the max_latency
computation in hci_conn_check_params, but was perfectly valid at the
time this mouse was qualified.
Before the patch, the mouse was extremely laggy, after the patch, the
mouse worked as expected.
Signed-off-by: Alain Michaud <alainm@chromium.org>
Reviewed-by: Miao-chen Chou <mcchou@chromium.org>
Tested-by: Harry Cutts <hcutts@chromium.org>
(am from https://patchwork.kernel.org/patch/12091711/)
(also found at https://lore.kernel.org/r/20210217142511.3221605-1-alainm@chromium.org)
BUG=b:179420794
TEST=Validated against the specific Lenovo Yoga Mouse
Change-Id: Id3b6d29418036424ea695561f03751612590a141
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/2706006
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Reviewed-by: Daniel Winkler <danielwinkler@google.com>
Tested-by: Alain Michaud <alainm@chromium.org>
Commit-Queue: Alain Michaud <alainm@chromium.org>
diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index f10d074..9baead6 100644
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -1510,6 +1510,36 @@
return hci_find_irk_by_rpa(hdev, bdaddr);
}
+/* Erratum 5412 which has been fixed in 4.2 changed the validation of
+ * connection parameters. For backwards compatibility reasons, the old
+ * calculation must be tolerated.
+ * For further details :
+ * https://www.bluetooth.org/errata/errata_view.cfm?errata_id=5419
+ */
+static inline int hci_check_conn_params_legacy(u16 min, u16 max, u16 latency,
+ u16 to_multiplier)
+{
+ u16 max_latency;
+
+ if (min > max || min < 6 || max > 3200)
+ return -EINVAL;
+
+ if (to_multiplier < 10 || to_multiplier > 3200)
+ return -EINVAL;
+
+ if (max >= to_multiplier * 8)
+ return -EINVAL;
+
+ max_latency = (to_multiplier * 8 / max) - 1;
+ if (latency > 499 || latency > max_latency)
+ return -EINVAL;
+
+ return 0;
+}
+
+/* Connection Parameter Validation Helper.
+ * See Vol 6, Part B, section 4.5.1.
+ */
static inline int hci_check_conn_params(u16 min, u16 max, u16 latency,
u16 to_multiplier)
{
diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 3d97a5b..4141281 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -5233,6 +5233,18 @@
memset(&rsp, 0, sizeof(rsp));
err = hci_check_conn_params(min, max, latency, to_multiplier);
+ if (err) {
+ BT_WARN("Invalid conn params min 0x%4.4x max 0x%4.4x latency: 0x%4.4x TO: 0x%4.4x",
+ min, max, latency, to_multiplier);
+
+ err = hci_check_conn_params_legacy(min, max, latency,
+ to_multiplier);
+ if (!err) {
+ /* latency is invalid, cap it to the max allowed */
+ latency = min(499, (to_multiplier * 4 / max) - 1);
+ }
+ }
+
if (err)
rsp.result = cpu_to_le16(L2CAP_CONN_PARAM_REJECTED);
else
