| Message ID | TYUPR06MB62175A4C6BC97FBAAC9DA72CD28D2@TYUPR06MB6217.apcprd06.prod.outlook.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v3] usb: gadget: u_serial: check Null pointer in EP callback | expand |
On 20-08-24 08:04 pm, 胡连勤 wrote: > From: Lianqin Hu <hulianqin@vivo.com> > > Added null pointer check to avoid system crash. > Still didn't update the commit text with reason for null pointer crash. Please mention about the race between gser_disconnect and read/write complete callbacks, and how the port can become Null. > 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 > You can also add the Fixes tag and CC stable kernel, so that it can be backported to older kernels (such as 5.15) also. https://www.kernel.org/doc/html/v4.10/process/submitting-patches.html#using-reported-by-tested-by-reviewed-by-suggested-by-and-fixes Please refer other commits for reference. > Signed-off-by: Lianqin Hu <hulianqin@vivo.com> > --- > v3: > - Add serial_port_lock protection when checking port pointer > - Optimize code comments > - Delete log printing > --- [...] > > @@ -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, Regards, Prashanth K
Hi Prashanth: >> Added null pointer check to avoid system crash. >> Still didn't update the commit text with reason for null pointer crash. >Please mention about the race between gser_disconnect and read/write complete callbacks, and how the port can become Null. >> 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 >You can also add the Fixes tag and CC stable kernel, so that it can be backported to older kernels (such as 5.15) also. usb: gadget: u_serial: Add null pointer check in gs_read_complete & gs_write_complete 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. Fixes: c1dca56 ("usb gadget: split out serial core") Cc: stable <stable@kernel.org> See if this description is feasible? Thanks
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; + + /* When port is NULL, return to avoid panic. */ + 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; + + /* When port is NULL, return to avoid panic. */ + 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,