From mboxrd@z Thu Jan 1 00:00:00 1970 From: Taehee Yoo Date: Fri, 9 Oct 2020 19:07:16 +0900 Subject: [PATCH net 000/117] net: avoid to remove module when its debugfs is being used In-Reply-To: <87r1q8gdqk.fsf@suse.de> References: <20201008155048.17679-1-ap420073@gmail.com> <1cbb69d83188424e99b2d2482848ae64@AcuMS.aculab.com> <62f6c2bd11ed8b25c1cd4462ebc6db870adc4229.camel@sipsolutions.net> <87r1q8gdqk.fsf@suse.de> Message-ID: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Nicolai Stange Cc: Johannes Berg , David Laight , "davem@davemloft.net" , "kuba@kernel.org" , "netdev@vger.kernel.org" , "linux-wireless@vger.kernel.org" , "wil6210@qti.qualcomm.com" , "b43-dev@lists.infradead.org" , "linux-bluetooth@vger.kernel.org" On Fri, 9 Oct 2020 at 14:39, Nicolai Stange wrote: > Hi Nicolai, Thank you for the review! > Taehee Yoo writes: > > > On Fri, 9 Oct 2020 at 01:14, Johannes Berg wrote: > > On Thu, 2020-10-08 at 15:59 +0000, David Laight wrote: > > > >> From: Taehee Yoo > >> > Sent: 08 October 2020 16:49 > >> > > >> > When debugfs file is opened, its module should not be removed until > >> > it's closed. > >> > Because debugfs internally uses the module's data. > >> > So, it could access freed memory. > > Yes, the file_operations' ->release() to be more specific -- that's not > covered by debugfs' proxy fops. > > > >> > In order to avoid panic, it just sets .owner to THIS_MODULE. > >> > So that all modules will be held when its debugfs file is opened. > >> > >> Can't you fix it in common code? > > > >> Yeah I was just wondering that too - weren't the proxy_fops even already > >> intended to fix this? > > > > I didn't try to fix this issue in the common code(debugfs). > > Because I thought It's a typical pattern of panic and THIS_MODULE > > can fix it clearly. > > So I couldn't think there is a root reason in the common code. > > That's correct, ->owner should get set properly, c.f. my other mail in > this thread. > Thanks a lot for verifying it! Taehee