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Date: Wed, 17 Jun 2020 19:13:12 +0530 From: Charan Teja Kalla <charante@...eaurora.org> To: David Laight <David.Laight@...LAB.COM>, "Ruhl, Michael J" <michael.j.ruhl@...el.com>, Sumit Semwal <sumit.semwal@...aro.org>, "open list:DMA BUFFER SHARING FRAMEWORK" <linux-media@...r.kernel.org>, DRI mailing list <dri-devel@...ts.freedesktop.org> Cc: Linaro MM SIG <linaro-mm-sig@...ts.linaro.org>, "vinmenon@...eaurora.org" <vinmenon@...eaurora.org>, LKML <linux-kernel@...r.kernel.org>, "stable@...r.kernel.org" <stable@...r.kernel.org> Subject: Re: [PATCH] dmabuf: use spinlock to access dmabuf->name On 6/17/2020 1:51 PM, David Laight wrote: > From: Charan Teja Kalla >> Sent: 17 June 2020 07:29 > ... >>>> If name is freed you will copy garbage, but the only way >>>> for that to happen is that _set_name or _release have to be called >>>> at just the right time. >>>> >>>> And the above would probably only be an issue if the set_name >>>> was called, so you will get NULL or a real name. >> >> And there exists a use-after-free to avoid which requires the lock. Say >> that memcpy() in dmabuffs_dname is in progress and in parallel _set_name >> will free the same buffer that memcpy is operating on. > > If the name is being looked at while the item is being freed > you almost certainly have much bigger problems that just > the name being a 'junk' pointer. True, thus needs the lock. > > David. > > - > Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK > Registration No: 1397386 (Wales) > -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project
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