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Message-ID: <48377484a8a9e479b301e9a9772653a3bc6ccf81.camel@linux.intel.com>
Subject: Re: [PATCH] platform/x86: ISST: fix use-after-free in
 tpmi_sst_dev_remove()
From: srinivas pandruvada <srinivas.pandruvada@linux.intel.com>
To: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>, Hans de Goede
	 <hdegoede@redhat.com>, Ilpo =?ISO-8859-1?Q?J=E4rvinen?=
	 <ilpo.jarvinen@linux.intel.com>, Zhang Rui <rui.zhang@intel.com>, 
	platform-driver-x86@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: dan.carpenter@linaro.org, kernel-janitors@vger.kernel.org, 
	error27@gmail.com
Date: Fri, 17 May 2024 07:31:14 -0700
In-Reply-To: <20240514092656.3462832-1-harshit.m.mogalapalli@oracle.com>
References: <20240514092656.3462832-1-harshit.m.mogalapalli@oracle.com>
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On Tue, 2024-05-14 at 02:26 -0700, Harshit Mogalapalli wrote:
> In tpmi_sst_dev_remove(), tpmi_sst is dereferenced after being freed.
> Fix this by reordering the kfree() post the dereference.
>=20
> Fixes: 9d1d36268f3d ("platform/x86: ISST: Support partitioned
> systems")
> Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>

> ---
> This is found by smatch and only compile tested.
> ---
> =C2=A0drivers/platform/x86/intel/speed_select_if/isst_tpmi_core.c | 2 +-
> =C2=A01 file changed, 1 insertion(+), 1 deletion(-)
>=20
> diff --git
> a/drivers/platform/x86/intel/speed_select_if/isst_tpmi_core.c
> b/drivers/platform/x86/intel/speed_select_if/isst_tpmi_core.c
> index 7bac7841ff0a..7fa360073f6e 100644
> --- a/drivers/platform/x86/intel/speed_select_if/isst_tpmi_core.c
> +++ b/drivers/platform/x86/intel/speed_select_if/isst_tpmi_core.c
> @@ -1610,8 +1610,8 @@ void tpmi_sst_dev_remove(struct
> auxiliary_device *auxdev)
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0tpmi_sst->partition_mask_=
current &=3D ~BIT(plat_info-
> >partition);
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0/* Free the package insta=
nce when the all partitions are
> removed */
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0if (!tpmi_sst->partition_=
mask_current) {
> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0kfree(tpmi_sst);
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0isst_common.sst_inst[tpmi_sst->package_id] =3D NULL=
;
> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0kfree(tpmi_sst);
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0}
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0mutex_unlock(&isst_tpmi_d=
ev_lock);
> =C2=A0}