6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ming Wang commit f75f21ef36285e5f56ee0c428bd2909ee81165b9 upstream. The MeiG Smart SRM821 5G module (0x2dee:0x4d53) crashes and drops off the USB bus when it receives a Zero Length Packet (ZLP) after sending or receiving an NTB of exactly 16384 bytes (tx_max). According to the MBIM specification, devices do not require a ZLP if the NTB size is exactly dwNtbOutMaxSize. However, the cdc_mbim driver defaults to sending ZLPs for devices not explicitly whitelisted to accommodate non-conformant hardware. This default behavior breaks the strictly conformant MeiG SRM821 module. Add this device to the ZLP conformance whitelist (cdc_mbim_info) so the driver will pad the NTB to avoid sending ZLPs, preventing the device firmware from crashing. Cc: stable@vger.kernel.org Signed-off-by: Ming Wang Link: https://patch.msgid.link/20260920074500.826121-1-wangming01@loongson.cn Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- drivers/net/usb/cdc_mbim.c | 5 +++++ 1 file changed, 5 insertions(+) --- a/drivers/net/usb/cdc_mbim.c +++ b/drivers/net/usb/cdc_mbim.c @@ -634,6 +634,11 @@ static const struct usb_device_id mbim_d .driver_info = (unsigned long)&cdc_mbim_info, }, + /* MeiG Smart SRM821 ZLP conformance */ + { USB_DEVICE_AND_INTERFACE_INFO(0x2dee, 0x4d53, USB_CLASS_COMM, USB_CDC_SUBCLASS_MBIM, USB_CDC_PROTO_NONE), + .driver_info = (unsigned long)&cdc_mbim_info, + }, + /* Some Huawei devices, ME906s-158 (12d1:15c1) and E3372 * (12d1:157d), are known to fail unless the NDP is placed * after the IP packets. Applying the quirk to all Huawei