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* [PATCH v4 0/3] Bluetooth: btmtk: fix ISO data reception
@ 2026-10-22  3:21 Chris Lu
  2026-10-22  3:21 ` [PATCH v4 1/3] Bluetooth: btmtk: drop zero-length ISO packets from endpoint padding Chris Lu
                   ` (3 more replies)
  0 siblings, 4 replies; 9+ messages in thread
From: Chris Lu @ 2026-10-22  3:21 UTC (permalink / raw)
  To: Marcel Holtmann, Johan Hedberg, Luiz Von Dentz
  Cc: Hao Qin, Wenlong Tian, Sean Wang, Will Lee, SS Wu,
	linux-bluetooth, linux-kernel, linux-mediatek, Chris Lu

Two fixes for btmtk_recv_isopkt(), found while debugging LE Audio on
MT7925, plus an update to the ISO data transmission setting. The function
is shared by every MediaTek USB controller that supports ISO data, so none
of this is specific to that part.

Patch 1 drops the zero padding that the ISO interrupt IN endpoint appends
to each transfer instead of parsing it as ISO packets.

Patch 2 bounds Data_Total_Length by hdev->iso_mtu.

Patch 3 updates the mt79xx ISO data transmission setting.

The three hunks do not overlap, so any prefix of the series applies on its
own.

Changes in v4:
- Patch 1: check for the endpoint's zero-filled padding before starting
  to parse a new frame, rather than after assembling a 4-byte header.
  Otherwise a zero-filled remainder shorter than an ISO header (1-3
  bytes) would be held across calls as a partial header and corrupt the
  next transfer's framing. This also avoids allocating and immediately
  freeing an skb for a fully zero-filled remainder.
- Patch 2, 3: unchanged.

Changes in v3:
- Patch 1: instead of dropping a packet solely because Data_Total_Length
  is zero, also confirm that the rest of the transfer is zero-filled
  before treating it as padding.
- Patch 2, 3: unchanged.

Changes in v2:
- Patch 2 reworked and retitled.
- Patch 3 added.

Based on bluetooth-next.

Chris Lu (3):
  Bluetooth: btmtk: drop zero-length ISO packets from endpoint padding
  Bluetooth: btmtk: bound the ISO payload length by the controller's MTU
  Bluetooth: btmtk: derive the firmware ISO setting from
    MTK_ISO_THRESHOLD

 drivers/bluetooth/btmtk.c | 44 ++++++++++++++++++++++++++++++++++-----
 1 file changed, 39 insertions(+), 5 deletions(-)

-- 
2.45.2


^ permalink raw reply	[flat|nested] 9+ messages in thread
* [PATCH v3 RESEND 1/3] Bluetooth: btmtk: drop zero-length ISO packets from endpoint padding
@ 2026-10-21  8:43 Chris Lu
  2026-10-21 13:00 ` Bluetooth: btmtk: fix ISO data reception bluez.test.bot
  0 siblings, 1 reply; 9+ messages in thread
From: Chris Lu @ 2026-10-21  8:43 UTC (permalink / raw)
  To: Marcel Holtmann, Johan Hedberg, Luiz Von Dentz
  Cc: Hao Qin, Wenlong Tian, Sean Wang, Will Lee, SS Wu,
	linux-bluetooth, linux-kernel, linux-mediatek, Chris Lu

The ISO interrupt IN endpoint delivers a fixed-size transfer that holds
one HCI ISO packet and zero-fills the remainder. That padding belongs to
the transfer rather than to the stream, so it has to be dropped instead of
reported to the host.

btmtk_recv_isopkt() keeps parsing it: the zero bytes read as an ISO header
with handle 0 and a Data_Total_Length of zero, and each one is passed to
hci_recv_frame() as a complete frame. A single transfer yields a long run
of them, which is what fills the HCI log with malformed ISO packets, and
iso_recv() drops the SDU it is reassembling whenever handle 0 belongs to a
live CIS/BIS.

A zero Data_Total_Length carries no ISO Data Load, so such a packet is
never part of the stream. Confirm that the rest of the transfer is
zero-filled before dropping it, since the padding runs to the end of the
transfer.

This was observed on MT7925, but btmtk_recv_isopkt() is shared by every
MediaTek USB controller that supports ISO data.

Fixes: ceac1cb0259d ("Bluetooth: btusb: mediatek: add ISO data transmission functions")
Co-developed-by: Hao Qin <hao.qin@mediatek.com>
Signed-off-by: Hao Qin <hao.qin@mediatek.com>
Co-developed-by: Wenlong Tian <ot_wenlong.tian@mediatek.com>
Signed-off-by: Wenlong Tian <ot_wenlong.tian@mediatek.com>
Signed-off-by: Chris Lu <chris.lu@mediatek.com>
---
 drivers/bluetooth/btmtk.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/drivers/bluetooth/btmtk.c b/drivers/bluetooth/btmtk.c
index 75483d8230e1..90463208385b 100644
--- a/drivers/bluetooth/btmtk.c
+++ b/drivers/bluetooth/btmtk.c
@@ -7,6 +7,7 @@
 #include <linux/usb.h>
 #include <linux/iopoll.h>
 #include <linux/overflow.h>
+#include <linux/string.h>
 #include <linux/unaligned.h>
 
 #include <net/bluetooth/bluetooth.h>
@@ -1588,6 +1589,25 @@ static int btmtk_recv_isopkt(struct hci_dev *hdev, void *buffer, int count)
 			/* Complete ISO header */
 			hci_skb_expect(skb) = __le16_to_cpu(dlen);
 
+			if (!hci_skb_expect(skb)) {
+				/* The interrupt endpoint zero-fills the
+				 * remainder of the transfer after the one
+				 * packet it carries. Confirm that is what
+				 * this is before dropping it.
+				 */
+				if (!mem_is_zero(buffer, count)) {
+					kfree_skb(skb);
+					skb = NULL;
+
+					err = -EILSEQ;
+					break;
+				}
+
+				kfree_skb(skb);
+				skb = NULL;
+				break;
+			}
+
 			if (skb_tailroom(skb) < hci_skb_expect(skb)) {
 				kfree_skb(skb);
 				skb = NULL;
-- 
2.45.2



^ permalink raw reply related	[flat|nested] 9+ messages in thread
* [PATCH v2 1/3] Bluetooth: btmtk: drop zero-length ISO packets from endpoint padding
@ 2026-10-15  8:14 Chris Lu
  2026-10-15 12:09 ` Bluetooth: btmtk: fix ISO data reception bluez.test.bot
  0 siblings, 1 reply; 9+ messages in thread
From: Chris Lu @ 2026-10-15  8:14 UTC (permalink / raw)
  To: Marcel Holtmann, Johan Hedberg, Luiz Von Dentz
  Cc: Hao Qin, Wenlong Tian, Sean Wang, Will Lee, SS Wu,
	linux-bluetooth, linux-kernel, linux-mediatek, Chris Lu

The ISO interrupt IN endpoint delivers a fixed-size transfer that holds
one HCI ISO packet and zero-fills the remainder. That padding belongs to
the transfer rather than to the stream, so it has to be dropped instead of
reported to the host.

btmtk_recv_isopkt() keeps parsing it: the zero bytes read as an ISO header
with handle 0 and a Data_Total_Length of zero, and each one is passed to
hci_recv_frame() as a complete frame. A single transfer yields a long run
of them, which is what fills the HCI log with malformed ISO packets, and
iso_recv() drops the SDU it is reassembling whenever handle 0 belongs to a
live CIS/BIS.

A zero Data_Total_Length carries no ISO Data Load, so such a packet is
never part of the stream. The padding runs to the end of the transfer, so
stop parsing once one is seen.

This was observed on MT7925, but btmtk_recv_isopkt() is shared by every
MediaTek USB controller that supports ISO data.

Fixes: ceac1cb0259d ("Bluetooth: btusb: mediatek: add ISO data transmission functions")
Co-developed-by: Hao Qin <hao.qin@mediatek.com>
Signed-off-by: Hao Qin <hao.qin@mediatek.com>
Co-developed-by: Wenlong Tian <ot_wenlong.tian@mediatek.com>
Signed-off-by: Wenlong Tian <ot_wenlong.tian@mediatek.com>
Signed-off-by: Chris Lu <chris.lu@mediatek.com>
---
 drivers/bluetooth/btmtk.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/bluetooth/btmtk.c b/drivers/bluetooth/btmtk.c
index bdc85147b97f..869eb2176379 100644
--- a/drivers/bluetooth/btmtk.c
+++ b/drivers/bluetooth/btmtk.c
@@ -1201,6 +1201,19 @@ static int btmtk_recv_isopkt(struct hci_dev *hdev, void *buffer, int count)
 			/* Complete ISO header */
 			hci_skb_expect(skb) = __le16_to_cpu(dlen);
 
+			/* The interrupt endpoint zero-fills the remainder of
+			 * each transfer, and that padding parses as a header
+			 * with a zero Data_Total_Length. Such a packet carries
+			 * no ISO Data Load at all and is never emitted by the
+			 * controller, so stop parsing here rather than hand a
+			 * bogus handle 0 packet to the stack.
+			 */
+			if (!hci_skb_expect(skb)) {
+				kfree_skb(skb);
+				skb = NULL;
+				break;
+			}
+
 			if (skb_tailroom(skb) < hci_skb_expect(skb)) {
 				kfree_skb(skb);
 				skb = NULL;
-- 
2.45.2


^ permalink raw reply related	[flat|nested] 9+ messages in thread
* [PATCH 1/2] Bluetooth: btmtk: drop zero-length ISO packets from endpoint padding
@ 2026-10-13  8:18 Chris Lu
  2026-10-13 11:53 ` Bluetooth: btmtk: fix ISO data reception bluez.test.bot
  0 siblings, 1 reply; 9+ messages in thread
From: Chris Lu @ 2026-10-13  8:18 UTC (permalink / raw)
  To: Marcel Holtmann, Johan Hedberg, Luiz Von Dentz
  Cc: Hao Qin, Wenlong Tian, Sean Wang, Will Lee, SS Wu,
	linux-bluetooth, linux-kernel, linux-mediatek, Chris Lu

The ISO interrupt IN endpoint delivers one HCI ISO packet per 264-byte
transfer and zero-fills the remainder. btmtk_recv_isopkt() keeps parsing
that padding: every four zero bytes look like an ISO header with handle 0
and Data_Total_Length 0, and are passed to hci_recv_frame() as a complete
frame. A single transfer can inject up to 64 of them, which is what fills
the HCI log with malformed ISO packets. If handle 0 belongs to a live
CIS/BIS, iso_recv() also drops the SDU it is reassembling.

A zero Data_Total_Length carries no ISO Data Load at all, and the
controller never emits one -- these are produced purely by parsing the
padding. The padding always runs to the end of the transfer, so stop
parsing once one is seen.

This was observed on MT7925, but btmtk_recv_isopkt() is shared by every
MediaTek USB controller that supports ISO data.

Fixes: ceac1cb0259d ("Bluetooth: btusb: mediatek: add ISO data transmission functions")
Co-developed-by: Hao Qin <hao.qin@mediatek.com>
Signed-off-by: Hao Qin <hao.qin@mediatek.com>
Co-developed-by: Wenlong Tian <ot_wenlong.tian@mediatek.com>
Signed-off-by: Wenlong Tian <ot_wenlong.tian@mediatek.com>
Signed-off-by: Chris Lu <chris.lu@mediatek.com>
---
 drivers/bluetooth/btmtk.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/bluetooth/btmtk.c b/drivers/bluetooth/btmtk.c
index bdc85147b97f..869eb2176379 100644
--- a/drivers/bluetooth/btmtk.c
+++ b/drivers/bluetooth/btmtk.c
@@ -1201,6 +1201,19 @@ static int btmtk_recv_isopkt(struct hci_dev *hdev, void *buffer, int count)
 			/* Complete ISO header */
 			hci_skb_expect(skb) = __le16_to_cpu(dlen);
 
+			/* The interrupt endpoint zero-fills the remainder of
+			 * each transfer, and that padding parses as a header
+			 * with a zero Data_Total_Length. Such a packet carries
+			 * no ISO Data Load at all and is never emitted by the
+			 * controller, so stop parsing here rather than hand a
+			 * bogus handle 0 packet to the stack.
+			 */
+			if (!hci_skb_expect(skb)) {
+				kfree_skb(skb);
+				skb = NULL;
+				break;
+			}
+
 			if (skb_tailroom(skb) < hci_skb_expect(skb)) {
 				kfree_skb(skb);
 				skb = NULL;
-- 
2.45.2


^ permalink raw reply related	[flat|nested] 9+ messages in thread

end of thread, other threads:[~2026-10-23 22:10 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-10-22  3:21 [PATCH v4 0/3] Bluetooth: btmtk: fix ISO data reception Chris Lu
2026-10-22  3:21 ` [PATCH v4 1/3] Bluetooth: btmtk: drop zero-length ISO packets from endpoint padding Chris Lu
2026-10-22  7:24   ` Bluetooth: btmtk: fix ISO data reception bluez.test.bot
2026-10-22  3:21 ` [PATCH v4 2/3] Bluetooth: btmtk: bound the ISO payload length by the controller's MTU Chris Lu
2026-10-22  3:21 ` [PATCH v4 3/3] Bluetooth: btmtk: derive the firmware ISO setting from MTK_ISO_THRESHOLD Chris Lu
2026-10-23 22:10 ` [PATCH v4 0/3] Bluetooth: btmtk: fix ISO data reception patchwork-bot+bluetooth
  -- strict thread matches above, loose matches on Subject: below --
2026-10-21  8:43 [PATCH v3 RESEND 1/3] Bluetooth: btmtk: drop zero-length ISO packets from endpoint padding Chris Lu
2026-10-21 13:00 ` Bluetooth: btmtk: fix ISO data reception bluez.test.bot
2026-10-15  8:14 [PATCH v2 1/3] Bluetooth: btmtk: drop zero-length ISO packets from endpoint padding Chris Lu
2026-10-15 12:09 ` Bluetooth: btmtk: fix ISO data reception bluez.test.bot
2026-10-13  8:18 [PATCH 1/2] Bluetooth: btmtk: drop zero-length ISO packets from endpoint padding Chris Lu
2026-10-13 11:53 ` Bluetooth: btmtk: fix ISO data reception bluez.test.bot

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