Re: [PATCH] rtlwifi: Fix null-pointer dereferences in error handling code of rtl_pci_probe()

[Larry Finger]

On 5/28/19 6:55 AM, Kalle Valo wrote:
> Jia-Ju Bai <baijiaju1990@xxxxxxxxx> wrote:
>
> > *BUG 1:
> > In rtl_pci_probe(), when rtlpriv->cfg->ops->init_sw_vars() fails,
> > rtl_deinit_core() in the error handling code is executed.
> > rtl_deinit_core() calls rtl_free_entries_from_scan_list(), which uses
> > rtlpriv->scan_list.list in list_for_each_entry_safe(), but it has been
> > initialized. Thus a null-pointer dereference occurs.
> > The reason is that rtlpriv->scan_list.list is initialized by
> > INIT_LIST_HEAD() in rtl_init_core(), which has not been called.
> >
> > To fix this bug, rtl_deinit_core() should not be called when
> > rtlpriv->cfg->ops->init_sw_vars() fails.
> >
> > *BUG 2:
> > In rtl_pci_probe(), rtl_init_core() can fail when rtl_regd_init() in
> > this function fails, and rtlpriv->scan_list.list has not been
> > initialized by INIT_LIST_HEAD(). Then, rtl_deinit_core() in the error
> > handling code of rtl_pci_probe() is executed. Finally, a null-pointer
> > dereference occurs due to the same reason of the above bug.
> >
> > To fix this bug, the initialization of lists in rtl_init_core() are
> > performed before the call to rtl_regd_init().
> >
> > These bugs are found by a runtime fuzzing tool named FIZZER written by
> > us.
> >
> > Signed-off-by: Jia-Ju Bai <baijiaju1990@xxxxxxxxx>
>
> Ping & Larry, is this ok to take?

Kalle,

Not at the moment. In reviewing the code, I was unable to see how this situation 
could develop, and his backtrace did not mention any rtlwifi code. For that 
reason, I asked him to add printk stat4ements to show the last part of rtl_pci 
that executed correctly. In 
https://marc.info/?l=linux-wireless&m=155788322631134&w=2, he promised to do 
that, but I have not seen the result.

Larry