Messages in this thread | | | Subject | Re: [PATCH] rtlwifi: Fix null-pointer dereferences in error handling code of rtl_pci_probe() | From | Jia-Ju Bai <> | Date | Wed, 29 May 2019 18:30:36 +0800 |
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On 2019/5/28 21:00, Larry Finger wrote: > On 5/28/19 6:55 AM, Kalle Valo wrote: >> Jia-Ju Bai <baijiaju1990@gmail.com> 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@gmail.com> >> >> 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. >
Hi Larry,
This patch is not related to the message you mentioned. That message is about an occasional crash that I reported. That crash occurred when request_irq() in rtl_pci_intr_mode_legacy() in rtl_pci_intr_mode_decide() fails. I have added printk statements and try to reproduce and debug that crash, but that crash does not always occur, and I still do not know the root cause of that crash.
The null-pointer dereferences fixed by this patch are different from that crash, and they always occur when the related functions fail. So please review these null-pointer dereferences, thanks :)
Best wishes, Jia-Ju Bai
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