Re: [PATCH v2] xhci: solve a double free problem while doing s4

[Zhangjiantao (Kirin, nanjing)]

On 2021/6/11 21:13, gregkh@xxxxxxxxxxxxxxxxxxx wrote :
> On Fri, Jun 11, 2021 at 11:08:30AM +0000, Zhangjiantao (Kirin, nanjing) wrote:
> > when system is doing s4, the process of xhci_resume may be as below:
> > 1、xhci_mem_cleanup
> > 2、xhci_init->xhci_mem_init->xhci_mem_cleanup(when memory is not enough).
> > xhci_mem_cleanup will be executed twice when system is out of memory.
> > xhci->port_caps is freed in xhci_mem_cleanup,but it isn't set to NULL.
> > It will be freed twice when xhci_mem_cleanup is called the second time.
> >
> > We got following bug when system resumes from s4:
> >
> > kernel BUG at mm/slub.c:309!
> > Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
> > CPU: 0 PID: 5929 Tainted: G S   W   5.4.96-arm64-desktop #1
> > pc : __slab_free+0x5c/0x424
> > lr : kfree+0x30c/0x32c
> >
> > Call trace:
> >   __slab_free+0x5c/0x424
> >   kfree+0x30c/0x32c
> >   xhci_mem_cleanup+0x394/0x3cc
> >   xhci_mem_init+0x9ac/0x1070
> >   xhci_init+0x8c/0x1d0
> >   xhci_resume+0x1cc/0x5fc
> >   xhci_plat_resume+0x64/0x70
> >   platform_pm_thaw+0x28/0x60
> >   dpm_run_callback+0x54/0x24c
> >   device_resume+0xd0/0x200
> >   async_resume+0x24/0x60
> >   async_run_entry_fn+0x44/0x110
> >   process_one_work+0x1f0/0x490
> >   worker_thread+0x5c/0x450
> >   kthread+0x158/0x160
> >   ret_from_fork+0x10/0x24
> >
> > Signed-off-by: Jiantao Zhang <water.zhangjiantao@xxxxxxxxxx>
> > Signed-off-by: Tao Xue <xuetao09@xxxxxxxxxx>
> > ---
> >   drivers/usb/host/xhci-mem.c | 1 +
> >   1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c index f66815f..e4b0c04 100644
> > --- a/drivers/usb/host/xhci-mem.c
> > +++ b/drivers/usb/host/xhci-mem.c
> > @@ -1924,6 +1924,7 @@ void xhci_mem_cleanup(struct xhci_hcd *xhci)
> >   	xhci->hw_ports = NULL;
> >   	xhci->rh_bw = NULL;
> >   	xhci->ext_caps = NULL;
> > +	xhci->port_caps = NULL;
> >   
> >   	xhci->page_size = 0;
> >   	xhci->page_shift = 0;
> > --
> > 2.7.4
>
> Hi,
>
> This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
> a patch that has triggered this response.  He used to manually respond
> to these common problems, but in order to save his sanity (he kept
> writing the same thing over and over, yet to different people), I was
> created.  Hopefully you will not take offence and will fix the problem
> in your patch and resubmit it so that it can be accepted into the Linux
> kernel tree.
>
> You are receiving this message because of the following common error(s)
> as indicated below:
>
> - This looks like a new version of a previously submitted patch, but you
>    did not list below the --- line any changes from the previous version.
>    Please read the section entitled "The canonical patch format" in the
>    kernel file, Documentation/SubmittingPatches for what needs to be done
>    here to properly describe this.
>
> If you wish to discuss this problem further, or you have questions about
> how to resolve this issue, please feel free to respond to this email and
> Greg will reply once he has dug out from the pending patches received
> from other developers.
>
> thanks,
>
> greg k-h's patch email bot

Yes,there is no change of code line. I only added
"Signed-off-by: Jiantao Zhang <water.zhangjiantao@xxxxxxxxxx>" in the comments.
thanks，
   Jiantao Zhang