From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jia-Ju Bai Subject: Re: [PATCH] hid: hid-core: Fix a sleep-in-atomic-context bug in __hid_request() Date: Thu, 6 Sep 2018 10:35:14 +0800 Message-ID: <6ec3d032-6d33-d2af-965f-7f3457dc8311@gmail.com> References: <20180901121659.1257-1-baijiaju1990@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Jiri Kosina Cc: benjamin.tissoires@redhat.com, linux-input@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-input@vger.kernel.org On 2018/9/5 16:29, Jiri Kosina wrote: > On Sat, 1 Sep 2018, Jia-Ju Bai wrote: > >> The driver may sleep with holding a spinlock. >> >> The function call paths (from bottom to top) in Linux-4.16 are: >> >> [FUNC] hid_alloc_report_buf(GFP_KERNEL) >> drivers/hid/hid-core.c, 1435: >> hid_alloc_report_buf in __hid_request >> ./include/linux/hid.h, 1023: >> __hid_request in hid_hw_request >> drivers/hid/hid-picolcd_core.c, 111: >> hid_hw_request in picolcd_send_and_wait >> drivers/hid/hid-picolcd_core.c, 100: >> _raw_spin_lock_irqsave in picolcd_send_and_wait >> >> [FUNC] hid_alloc_report_buf(GFP_KERNEL) >> drivers/hid/hid-core.c, 1435: >> hid_alloc_report_buf in __hid_request >> ./include/linux/hid.h, 1023: >> __hid_request in hid_hw_request >> drivers/hid/hid-picolcd_core.c, 245: >> hid_hw_request in picolcd_reset >> drivers/hid/hid-picolcd_core.c, 235: >> _raw_spin_lock_irqsave in picolcd_reset >> >> [FUNC] hid_alloc_report_buf(GFP_KERNEL) >> drivers/hid/hid-core.c, 1435: >> hid_alloc_report_buf in __hid_request >> ./include/linux/hid.h, 1023: >> __hid_request in hid_hw_request >> drivers/hid/hid-picolcd_fb.c, 215: >> hid_hw_request in picolcd_fb_reset >> drivers/hid/hid-picolcd_fb.c, 206: >> _raw_spin_lock_irqsave in picolcd_fb_reset >> >> [FUNC] hid_alloc_report_buf(GFP_KERNEL) >> drivers/hid/hid-core.c, 1435: >> hid_alloc_report_buf in __hid_request >> ./include/linux/hid.h, 1023: >> __hid_request in hid_hw_request >> drivers/hid/hid-lg4ff.c, 465: >> hid_hw_request in lg4ff_play >> drivers/hid/hid-lg4ff.c, 441: >> _raw_spin_lock_irqsave in lg4ff_play >> >> To fix this bug, GFP_KERNEL is replaced with GFP_ATOMIC. >> >> This bug is found by my static analysis tool DSAC. > Could you please rewrite the changelog so that it's human readable? The > above is a bit hard to understand, I think something along the lines of > "__hid_request() has to be allocating with GFP_ATOMIC because there are > the following callchains leading to __hid_request() being an atomic > context: ... a->b->c.._hid_request()" etc. > Okay, I will send a new patch. Best wishes, Jia-Ju Bai