Re: 答复: [PATCH v1] usb: gadget: u_serial: check Null pointer in EP callback

["gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>]

On Tue, Aug 20, 2024 at 09:13:36AM +0000, 胡连勤 wrote:
> Hello linux community expert:
> 
> >> Added null pointer check to avoid system crash.
> >> 
> >> 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
> >> 
> >> Signed-off-by: Lianqin Hu <hulianqin@vivo.com>
> >> ---
> >> v1:
> >   - Optimize code comments, delete log printing
> 
> >Also, same comment as before, what:
> >  - causes port to be NULL
>    When unbind, the gser_unbind function call gserial_disconnect to set gser->ioport = NULL, and struct gs_port *port = gser->ioport, resulting in port being NULL.
>    It seems that there is a potential competition between the gs_read_complete function and the gserial_disconnect function.

Then fix that properly please.