Hi Dan, thx for your review.
On 22/04/14 06:42PM, Dan Carpenter wrote:
> On Thu, Apr 14, 2022 at 10:12:23PM +0800, Wang Cheng wrote:
> > Due to the case that "requesttype == 0x01 && status <= 0"
> > isn't handled in r8712_usbctrl_vendorreq(),
> > "data" (drivers/staging/rtl8712/usb_ops.c:32)
> > will be returned without initialization.
> >
> > When "tmpU1b" (drivers/staging/rtl8712/usb_intf.c:395)
> > is 0, mac[6] (usb_intf.c:394) won't be initialized,
> > which leads to accessing uninit-value on usb_intf.c:541.
>
> These line numbers are sort of useless because everyone is on a
> different git hash.
I will correct this.
>
> >
> > Reported-and-tested-by: syzbot+6f5ecd144854c0d8580b@xxxxxxxxxxxxxxxxxxxxxxxxx
> > Signed-off-by: Wang Cheng <wanngchenng@xxxxxxxxx>
> > ---
> > drivers/staging/rtl8712/usb_intf.c | 6 +++---
> > drivers/staging/rtl8712/usb_ops_linux.c | 14 ++++++++------
> > 2 files changed, 11 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/staging/rtl8712/usb_intf.c b/drivers/staging/rtl8712/usb_intf.c
> > index ee4c61f85a07..50dcd3ecb685 100644
> > --- a/drivers/staging/rtl8712/usb_intf.c
> > +++ b/drivers/staging/rtl8712/usb_intf.c
> > @@ -538,13 +538,13 @@ static int r871xu_drv_init(struct usb_interface *pusb_intf,
> > } else {
> > AutoloadFail = false;
> > }
> > - if (((mac[0] == 0xff) && (mac[1] == 0xff) &&
> > + if ((!AutoloadFail) ||
> > + ((mac[0] == 0xff) && (mac[1] == 0xff) &&
> > (mac[2] == 0xff) && (mac[3] == 0xff) &&
> > (mac[4] == 0xff) && (mac[5] == 0xff)) ||
> > ((mac[0] == 0x00) && (mac[1] == 0x00) &&
> > (mac[2] == 0x00) && (mac[3] == 0x00) &&
> > - (mac[4] == 0x00) && (mac[5] == 0x00)) ||
> > - (!AutoloadFail)) {
> > + (mac[4] == 0x00) && (mac[5] == 0x00))) {
> > mac[0] = 0x00;
> > mac[1] = 0xe0;
> > mac[2] = 0x4c;
>
> This is a separate fix from the rest of the patch. Send it by itself.
Ah, thought to send a patch series.
>
>
> > diff --git a/drivers/staging/rtl8712/usb_ops_linux.c b/drivers/staging/rtl8712/usb_ops_linux.c
> > index f984a5ab2c6f..e321ca4453ca 100644
> > --- a/drivers/staging/rtl8712/usb_ops_linux.c
> > +++ b/drivers/staging/rtl8712/usb_ops_linux.c
> > @@ -495,12 +495,14 @@ int r8712_usbctrl_vendorreq(struct intf_priv *pintfpriv, u8 request, u16 value,
> > }
> > status = usb_control_msg(udev, pipe, request, reqtype, value, index,
> > pIo_buf, len, 500);
> > - if (status > 0) { /* Success this control transfer. */
> > - if (requesttype == 0x01) {
> > - /* For Control read transfer, we have to copy the read
> > - * data from pIo_buf to pdata.
> > - */
> > - memcpy(pdata, pIo_buf, status);
> > + /* For Control read transfer, copy the read data from pIo_buf to pdata
> > + * when control transfer success; otherwise init *pdata with 0.
> > + */
> > + if (requesttype == 0x01) {
> > + if (status > 0)
> > + memcpy(pdata, pIo_buf, status);
> > + else
> > + *(u32 *)pdata = 0;
> > }
>
> This isn't really correct. In many cases status is "len" is less than 4.
> I'm slightly surprised that nothing complains about that as an
> uninitialized access. But then another problem is that "status" can be
> less than "len".
Sorry, I should explain it clearly. If I did right, watching "status"
with gdb while running syzkaller reproducer, "status" returns from
usb_control_msg() is -71. In which case, *pdata won't be touched in
r8712_usbctrl_vendorreq(). As a result, "data" in
usb_read8()/usb_read16()/usb_read32() will be returned without
initialization. I think that is why kmsan reports:
Local variable data created at:
usb_read8+0x5d/0x130 drivers/staging/rtl8712/usb_ops.c:33
r8712_read8+0xa5/0xd0 drivers/staging/rtl8712/rtl8712_io.c:29
>
> A better fix instead of setting pdata to zero would be to add error
> checking in the callers and then change this code to use
> usb_control_msg_send/recv(). Probably just initialize "data" in the
> callers as well.
I tried something similar which also works fine, but I think this patch
does't fix it at root.
https://syzkaller.appspot.com/text?tag=Patch&x=15be2970f00000
>
> regards,
> dan carpenter
>
thanks,
-- w
