linux-hardening - Re: [PATCH] usb: musb: Check requset->buf before use to avoid crash issue

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Message-ID: <CANnj+8Q1-5OX1BOM_12zA2v7D38y8rJctXn2_ja71P6UkzEyfw@mail.gmail.com>
Date: Mon, 30 Oct 2023 09:52:22 +0800
From: xingxing luo <xingxing0070.luo@...il.com>
To: Greg KH <gregkh@...uxfoundation.org>
Cc: Xingxing Luo <xingxing.luo@...soc.com>, b-liu@...com, keescook@...omium.org, 
	nathan@...nel.org, ndesaulniers@...gle.com, trix@...hat.com, 
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-hardening@...r.kernel.org, llvm@...ts.linux.dev, Zhiyong.Liu@...soc.com, 
	Cixi.Geng1@...soc.com, Orson.Zhai@...soc.com, zhang.lyra@...il.com
Subject: Re: [PATCH] usb: musb: Check requset->buf before use to avoid crash issue

On Fri, Oct 27, 2023 at 6:54 PM Greg KH <gregkh@...uxfoundation.org> wrote:
>
> On Mon, Oct 23, 2023 at 05:31:53PM +0800, Xingxing Luo wrote:
> > When connecting USB to PC, there is a very low probability of kernel
> > crash. The reason is that in ep0_txstate(), the buf member of struct
> > usb_request used may be a null pointer. Therefore, it needs to
> > determine whether it is null before using it.
> >
> > [ 4888.071462][T597@C0] Call trace:
> > [ 4888.071467][T597@C0]  musb_default_write_fifo+0xa0/0x1ac [musb_hdrc]
> > [ 4888.087190][T597@C0]  musb_write_fifo+0x3c/0x90 [musb_hdrc]
> > [ 4888.099826][T597@C0]  ep0_txstate+0x78/0x218 [musb_hdrc]
> > [ 4888.153918][T597@C0]  musb_g_ep0_irq+0x3c4/0xe10 [musb_hdrc]
> > [ 4888.159663][T597@C0]  musb_interrupt+0xab4/0xf1c [musb_hdrc]
> > [ 4888.165391][T597@C0]  sprd_musb_interrupt+0x1e4/0x484 [musb_sprd]
> > [ 4888.171447][T597@C0]  __handle_irq_event_percpu+0xd8/0x2f8
> > [ 4888.176901][T597@C0]  handle_irq_event+0x70/0xe4
> > [ 4888.181487][T597@C0]  handle_fasteoi_irq+0x15c/0x230
> > [ 4888.186420][T597@C0]  handle_domain_irq+0x88/0xfc
> > [ 4888.191090][T597@C0]  gic_handle_irq+0x60/0x138
> > [ 4888.195591][T597@C0]  call_on_irq_stack+0x40/0x70
> > [ 4888.200263][T597@C0]  do_interrupt_handler+0x50/0xac
> > [ 4888.205196][T597@C0]  el1_interrupt+0x34/0x64
> > [ 4888.209524][T597@C0]  el1h_64_irq_handler+0x1c/0x2c
> > [ 4888.214370][T597@C0]  el1h_64_irq+0x7c/0x80
> > [ 4888.218525][T597@C0]  __check_heap_object+0x1ac/0x1fc
> > [ 4888.223544][T597@C0]  __check_object_size+0x10c/0x20c
> > [ 4888.228563][T597@C0]  simple_copy_to_iter+0x40/0x74
> > [ 4888.233410][T597@C0]  __skb_datagram_iter+0xa0/0x310
> > [ 4888.238343][T597@C0]  skb_copy_datagram_iter+0x44/0x110
> > [ 4888.243535][T597@C0]  netlink_recvmsg+0xdc/0x364
> > [ 4888.248123][T597@C0]  ____sys_recvmsg.llvm.16749613423860851707+0x358/0x6c0
> > [ 4888.255045][T597@C0]  ___sys_recvmsg+0xe0/0x1dc
> > [ 4888.259544][T597@C0]  __arm64_sys_recvmsg+0xc4/0x10c
> > [ 4888.264478][T597@C0]  invoke_syscall+0x6c/0x15c
> > [ 4888.268976][T597@C0]  el0_svc_common.llvm.12373701176611417606+0xd4/0x120
> > [ 4888.275726][T597@C0]  do_el0_svc+0x34/0xac
> > [ 4888.279795][T597@C0]  el0_svc+0x28/0x90
> > [ 4888.283603][T597@C0]  el0t_64_sync_handler+0x88/0xec
> > [ 4888.288548][T597@C0]  el0t_64_sync+0x1b4/0x1b8
> > [ 4888.292956][T597@C0] Code: 540002c3 53027ea8 aa1303e9 71000508 (b840452a)
> > [ 4888.299789][T597@C0] ---[ end trace 14a301b7253e83cc ]---
> >
> > Signed-off-by: Xingxing Luo <xingxing.luo@...soc.com>
> > ---
> >  drivers/usb/musb/musb_gadget_ep0.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/drivers/usb/musb/musb_gadget_ep0.c b/drivers/usb/musb/musb_gadget_ep0.c
> > index 6d7336727388..5d0629866128 100644
> > --- a/drivers/usb/musb/musb_gadget_ep0.c
> > +++ b/drivers/usb/musb/musb_gadget_ep0.c
> > @@ -531,6 +531,11 @@ static void ep0_txstate(struct musb *musb)
> >
> >       request = &req->request;
> >
> > +     if (!requset->buf) {
> > +             musb_dbg(musb, "request->buf is NULL");
> > +             return;
> > +     }
> > +
> >       /* load the data */
> >       fifo_src = (u8 *) request->buf + request->actual;
> >       fifo_count = min((unsigned) MUSB_EP0_FIFOSIZE,
> > --
> > 2.17.1
>
> This patch does not even build, how did you test it?
>

I have verified this patch on our platform, which is unisoc, and it
can fix the kernel crash problem. However, it seems that there is a
spelling error in this patch, I will fix it in the next version.

> And what commit id does this fix?

commit id: 550a7375fe720924241f0eb76e4a5c1a3eb8c32f

>
> thanks,
>
> greg k-h