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([2402:f000:1:1501:200:5efe:a66f:460b]) by smtp.gmail.com with ESMTPSA id g4-v6sm1924943pgc.8.2018.06.20.03.05.35 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 20 Jun 2018 03:05:38 -0700 (PDT) Subject: Re: [PATCH] staging: rtl8723bs: Fix two possible sleep-in-atomic-context bugs in translate_scan() To: Dan Carpenter , cocci@systeme.lip6.fr, Julia Lawall Cc: gregkh@linuxfoundation.org, quytelda@tamalin.org, Larry.Finger@lwfinger.net, harshasharmaiitr@gmail.com, arushisinghal19971997@gmail.com, amitoj1606@gmail.com, jeremy.lefaure@lse.epita.fr, teo.dacquet@gmail.com, devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org References: <20180620095016.8484-1-baijiaju1990@gmail.com> <20180620095650.fga6xi7fyjgybs76@mwanda> From: Jia-Ju Bai Message-ID: Date: Wed, 20 Jun 2018 18:05:06 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.2.0 MIME-Version: 1.0 In-Reply-To: <20180620095650.fga6xi7fyjgybs76@mwanda> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 >> --- >> 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