[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <dd6eaaad-413e-bd5d-d0f4-0a6d05438395@gmail.com>
Date: Wed, 20 Jun 2018 18:05:06 +0800
From: Jia-Ju Bai <baijiaju1990@...il.com>
To: Dan Carpenter <dan.carpenter@...cle.com>, cocci@...teme.lip6.fr,
Julia Lawall <Julia.Lawall@...6.fr>
Cc: gregkh@...uxfoundation.org, quytelda@...alin.org,
Larry.Finger@...inger.net, harshasharmaiitr@...il.com,
arushisinghal19971997@...il.com, amitoj1606@...il.com,
jeremy.lefaure@....epita.fr, teo.dacquet@...il.com,
devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] staging: rtl8723bs: Fix two possible
sleep-in-atomic-context bugs in translate_scan()
On 2018/6/20 17:56, Dan Carpenter wrote:
> On Wed, Jun 20, 2018 at 05:50:16PM +0800, Jia-Ju Bai wrote:
>> The driver may sleep with holding a spinlock.
>> The function call paths (from bottom to top) in Linux-4.16.7 are:
>>
>> [FUNC] kzalloc(GFP_KERNEL)
>> drivers/staging/rtl8723bs/os_dep/ioctl_linux.c, 323:
>> kzalloc in translate_scan
>> drivers/staging/rtl8723bs/os_dep/ioctl_linux.c, 1554:
>> translate_scan in rtw_wx_get_scan
>> drivers/staging/rtl8723bs/os_dep/ioctl_linux.c, 1533:
>> spin_lock_bh in rtw_wx_get_scan
>>
>> [FUNC] kzalloc(GFP_KERNEL)
>> drivers/staging/rtl8723bs/os_dep/ioctl_linux.c, 455:
>> kzalloc in translate_scan
>> drivers/staging/rtl8723bs/os_dep/ioctl_linux.c, 1554:
>> translate_scan in rtw_wx_get_scan
>> drivers/staging/rtl8723bs/os_dep/ioctl_linux.c, 1533:
>> spin_lock_bh in rtw_wx_get_scan
>>
>> To fix these bugs, GFP_KERNEL is replaced with GFP_ATOMIC.
>>
>> These bugs are found by my static analysis tool (DSAC-2) and checked by
>> my code review.
>>
>> Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>
>> ---
>> drivers/staging/rtl8723bs/os_dep/ioctl_linux.c | 4 ++--
>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c b/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c
>> index b26533983864..7632b8974563 100644
>> --- a/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c
>> +++ b/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c
>> @@ -321,7 +321,7 @@ static char *translate_scan(struct adapter *padapter,
>> RT_TRACE(_module_rtl871x_mlme_c_, _drv_info_, ("rtw_wx_get_scan: ssid =%s\n", pnetwork->network.Ssid.Ssid));
>> RT_TRACE(_module_rtl871x_mlme_c_, _drv_info_, ("rtw_wx_get_scan: wpa_len =%d rsn_len =%d\n", wpa_len, rsn_len));
>>
>> - buf = kzalloc(MAX_WPA_IE_LEN*2, GFP_KERNEL);
>> + buf = kzalloc(MAX_WPA_IE_LEN*2, GFP_ATOMIC);
>> if (!buf)
>> return start;
> Thanks! It occurs to me that another way to detect this bug is that
> one of the allocations in this function already uses GFP_ATOMIC. It
> doesn't normally make sense to mix GFP_ATOMIC and GFP_KERNEL when there
> isn't any locking in the function.
Yes, this pattern is interesting for bug finding :)
But to fix the bugs of this pattern, we need to decide whether
GFP_ATOMIC or GFP_KERNEL should be used here.
Best wishes,
Jia-Ju Bai
Powered by blists - more mailing lists