From: Hou Tao <houtao1@huawei.com>
To: Wen Yang <wenyang@linux.alibaba.com>,
Richard Weinberger <richard@nod.at>,
Miquel Raynal <miquel.raynal@bootlin.com>,
Vignesh Raghavendra <vigneshr@ti.com>
Cc: linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org,
xlpang@linux.alibaba.com
Subject: Re: [PATCH] UBI: fix use after free in ubi_remove_volume()
Date: Thu, 5 Dec 2019 09:33:18 +0800 [thread overview]
Message-ID: <58208ceb-4d72-c4a1-8a2b-9e38854e3672@huawei.com> (raw)
In-Reply-To: <65b49705-e28c-e077-c0de-c5167e34d1c5@huawei.com>
Hi,
On 2019/12/3 21:13, Hou Tao wrote:
> Reviewed-by: Hou Tao <houtao1@huawei.com>
>
Sorry for my early conclusion.
The reference of ubi_volume had already been increased in ubi_open_volume()
in ubi_cdev_ioctl(), so this reference dropped in ubi_remove_volume() will not
be the last one, and there will no use-after-free problem.
Regards,
Tao
> On 2019/11/30 17:33, Wen Yang wrote:
>> We can't use "vol" after it has been freed.
>>
>> Fixes: 493cfaeaa0c9 ("mtd: utilize new cdev_device_add helper function")
>> Signed-off-by: Wen Yang <wenyang@linux.alibaba.com>
>> Cc: Richard Weinberger <richard@nod.at>
>> Cc: Miquel Raynal <miquel.raynal@bootlin.com>
>> Cc: Vignesh Raghavendra <vigneshr@ti.com>
>> Cc: linux-mtd@lists.infradead.org
>> Cc: linux-kernel@vger.kernel.org
>> ---
>> drivers/mtd/ubi/vmt.c | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/mtd/ubi/vmt.c b/drivers/mtd/ubi/vmt.c
>> index 139ee13..8ff1478 100644
>> --- a/drivers/mtd/ubi/vmt.c
>> +++ b/drivers/mtd/ubi/vmt.c
>> @@ -375,7 +375,6 @@ int ubi_remove_volume(struct ubi_volume_desc *desc, int no_vtbl)
>> }
>>
>> cdev_device_del(&vol->cdev, &vol->dev);
>> - put_device(&vol->dev);
>>
>> spin_lock(&ubi->volumes_lock);
>> ubi->rsvd_pebs -= reserved_pebs;
>> @@ -388,6 +387,8 @@ int ubi_remove_volume(struct ubi_volume_desc *desc, int no_vtbl)
>> if (!no_vtbl)
>> self_check_volumes(ubi);
>>
>> + put_device(&vol->dev);
>> +
>> return 0;
>>
>> out_err:
>>
>
>
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> http://lists.infradead.org/mailman/listinfo/linux-mtd/
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>
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prev parent reply other threads:[~2019-12-05 1:33 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-30 9:33 [PATCH] UBI: fix use after free in ubi_remove_volume() Wen Yang
2019-12-03 13:13 ` Hou Tao
2019-12-05 1:33 ` Hou Tao [this message]
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