From: Lianqin Hu <hulianqin@xxxxxxxx> Considering that in some extreme cases, when the unbind operation is being executed, gserial_disconnect has already cleared gser->ioport, and the controller has not stopped & pullup 0, sys.usb.config is reset and the bind operation will be re-executed, calling gs_read_complete, which will result in accessing gser->iport, resulting in a null pointer dereference, add a null pointer check to prevent this situation. Added a static spinlock to prevent gser->ioport from becoming null after the newly added check. Unable to handle kernel NULL pointer dereference at virtual address 00000000000001a8 pc : gs_read_complete+0x58/0x240 lr : usb_gadget_giveback_request+0x40/0x160 sp : ffffffc00f1539c0 x29: ffffffc00f1539c0 x28: ffffff8002a30000 x27: 0000000000000000 x26: ffffff8002a30000 x25: 0000000000000000 x24: ffffff8002a30000 x23: ffffff8002ff9a70 x22: ffffff898e7a7b00 x21: ffffff803c9af9d8 x20: ffffff898e7a7b00 x19: 00000000000001a8 x18: ffffffc0099fd098 x17: 0000000000001000 x16: 0000000080000000 x15: 0000000ac1200000 x14: 0000000000000003 x13: 000000000000d5e8 x12: 0000000355c314ac x11: 0000000000000015 x10: 0000000000000012 x9 : 0000000000000008 x8 : 0000000000000000 x7 : 0000000000000000 x6 : ffffff887cd12000 x5 : 0000000000000002 x4 : ffffffc00f9b07f0 x3 : ffffffc00f1538d0 x2 : 0000000000000001 x1 : 0000000000000000 x0 : 00000000000001a8 Call trace: gs_read_complete+0x58/0x240 usb_gadget_giveback_request+0x40/0x160 dwc3_remove_requests+0x170/0x484 dwc3_ep0_out_start+0xb0/0x1d4 __dwc3_gadget_start+0x25c/0x720 kretprobe_trampoline.cfi_jt+0x0/0x8 kretprobe_trampoline.cfi_jt+0x0/0x8 udc_bind_to_driver+0x1d8/0x300 usb_gadget_probe_driver+0xa8/0x1dc gadget_dev_desc_UDC_store+0x13c/0x188 configfs_write_iter+0x160/0x1f4 vfs_write+0x2d0/0x40c ksys_write+0x7c/0xf0 __arm64_sys_write+0x20/0x30 invoke_syscall+0x60/0x150 el0_svc_common+0x8c/0xf8 do_el0_svc+0x28/0xa0 el0_svc+0x24/0x84 el0t_64_sync_handler+0x88/0xec el0t_64_sync+0x1b4/0x1b8 Code: aa1f03e1 aa1303e0 52800022 2a0103e8 (88e87e62) ---[ end trace 938847327a739172 ]--- Kernel panic - not syncing: Oops: Fatal exception Fixes: c1dca562be8a ("usb gadget: split out serial core") Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Lianqin Hu <hulianqin@xxxxxxxx> --- v7: - Remove code comments - Update the commit text - Add the Fixes tag - CC stable kernel - Add serial_port_lock protection when checking port pointer - Optimize code comments - Delete log printing --- drivers/usb/gadget/function/u_serial.c | 33 ++++++++++++++++++++++---- 1 file changed, 28 insertions(+), 5 deletions(-) diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c index b394105e55d6..e43d8065f7ec 100644 --- a/drivers/usb/gadget/function/u_serial.c +++ b/drivers/usb/gadget/function/u_serial.c @@ -452,20 +452,43 @@ static void gs_rx_push(struct work_struct *work) static void gs_read_complete(struct usb_ep *ep, struct usb_request *req) { - struct gs_port *port = ep->driver_data; + struct gs_port *port; + unsigned long flags; + + spin_lock_irqsave(&serial_port_lock, flags); + port = ep->driver_data; + + if (!port) { + spin_unlock_irqrestore(&serial_port_lock, flags); + return; + } - /* Queue all received data until the tty layer is ready for it. */ spin_lock(&port->port_lock); + spin_unlock(&serial_port_lock); + + /* Queue all received data until the tty layer is ready for it. */ list_add_tail(&req->list, &port->read_queue); schedule_delayed_work(&port->push, 0); - spin_unlock(&port->port_lock); + spin_unlock_irqrestore(&port->port_lock, flags); } static void gs_write_complete(struct usb_ep *ep, struct usb_request *req) { - struct gs_port *port = ep->driver_data; + struct gs_port *port; + unsigned long flags; + + spin_lock_irqsave(&serial_port_lock, flags); + port = ep->driver_data; + + if (!port) { + spin_unlock_irqrestore(&serial_port_lock, flags); + return; + } spin_lock(&port->port_lock); + spin_unlock(&serial_port_lock); list_add(&req->list, &port->write_pool); port->write_started--; @@ -486,7 +509,7 @@ static void gs_write_complete(struct usb_ep *ep, struct usb_request *req) break; } - spin_unlock(&port->port_lock); + spin_unlock_irqrestore(&port->port_lock, flags); } static void gs_free_requests(struct usb_ep *ep, struct list_head *head, -- 2.39.0