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Date:   Wed, 28 Jul 2021 12:35:07 +0200
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Subject: Re: [PATCH] iommu: check if group is NULL before remove device
To:     Joerg Roedel <joro@8bytes.org>
CC:     iommu@lists.linux-foundation.org,
        Frank Wunderlich <frank-w@public-files.de>,
        Will Deacon <will@kernel.org>, linux-kernel@vger.kernel.org,
        yong.wu@mediatek.com
From:   Frank Wunderlich <linux@fw-web.de>
Message-ID: <F2ABC95E-D39F-4713-8959-91366DE4ECB8@fw-web.de>
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Hi Joerg,

Sorry for late reply, somehow i marked message as read without answering i=
t=2E

Am 15=2E Juli 2021 09:20:04 MESZ schrieb Joerg Roedel <joro@8bytes=2Eorg>:
>On Thu, Jul 15, 2021 at 09:11:50AM +0200, Frank Wunderlich wrote:
>> From: Frank Wunderlich <frank-w@public-files=2Ede>
>>=20
>> if probe is failing, iommu_group may be not initialized,
>
>Sentences start with capital letters=2E
>
>IOMMU patch subjects too, after the 'iommu:' prefix=2E

Will fix these in v2

>> so freeing it will result in NULL pointer access
>
>Please describe in more detail how this NULL-ptr dereference is
>triggered=2E

I had this by testing this series:=20
https://patchwork=2Ekernel=2Eorg/project/linux-mediatek/list/?series=3D515=
129

Initialization in mtk driver was failed (i guess the iommu group was not y=
et created), cleanup was started and so this function is called with a NULL=
 group pointer=2E I can try to find my debug-trace if you need a kind of ba=
cktrace=2E

regards Frank