From: Yu Chen <chyyuu@gmail.com>
To: "Kai Mäkisara (Kolumbus)" <kai.makisara@kolumbus.fi>
Cc: 徐永健 <xuyongjiande@gmail.com>,
"James E.J. Bottomley" <JBottomley@parallels.com>,
linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org
Subject: Re: [PATCH] scsi: int overflow in st_ioctl()
Date: Wed, 18 Dec 2013 12:00:20 +0800 [thread overview]
Message-ID: <CAAdffVH3pPpvu+GWwikPpGynTRRMW2unbyRvP2jQWpUU-=R6qw@mail.gmail.com> (raw)
In-Reply-To: <F1B567DD-C322-4BA7-BFEA-E7C4B1F82697@kolumbus.fi>
Because the local variable of st_int_ioctl function, such as long ltmp
be assigned by arg.
I think we should limit the parameter arg of st_int_ioctl function to
the range of 24-bit signed integer.
Yong Jianxu, please update your patch.
2013/12/18 "Kai Mäkisara (Kolumbus)" <kai.makisara@kolumbus.fi>:
> On 17.12.2013, at 16.43, Yongjian Xu xuyongjiande@gmail.com wrote:
>
>> From: Yongjian Xu <xuyongjiande@gmail.com>
>>
>> mtc.mt_count comes from user-space.
>> int overflow may occur:
>> mtc.mt_count++;
>> mtc.mt_count—;
>
> I agree that this is a problem. However, it seems that there is also another problem: the SPACE command uses a 24-bit count field and this overflows far below INT_MAX. Should the count in MTFSF etc. be limited to (2<<24-2)? This would make the checks you suggest unnecessary. (-2 so that the behavior does not depend on whether we are at file mark or not.)
>
> I am a bit hesitant with this suggestion because someone may use count INT_MAX to space to the end of the tape. This probably succeeds now but after the fix it would return an error.
>
> Thanks,
> Kai
>
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--
Best Regards
==============================================
Yu Chen
Ph.D. Associate Professor
System Software&Software Engineering Group,
Dept. of Computer Science and Technology
Tsinghua University, Beijing 100084, P.R. China
E-Mail: mailto:yuchen@tsinghua.edu.cn chyyuu@gmail.com
==============================================
prev parent reply other threads:[~2013-12-18 4:00 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1387291383-25126-1-git-send-email-xuyongjiande@gmail.com>
2013-12-17 17:53 ` [PATCH] scsi: int overflow in st_ioctl() "Kai Mäkisara (Kolumbus)"
2013-12-18 4:00 ` Yu Chen [this message]
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