linux-kernel - Re: [PATCH RFC] random: fix syzkaller fuzzer test int overflow

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Date:   Wed, 25 Oct 2017 14:30:56 +0800
From:   Chen Feng <puck.chen@...ilicon.com>
To:     "Theodore Ts'o" <tytso@....edu>,
        Greg KH <gregkh@...uxfoundation.org>, <zhaoyukun@...wei.com>,
        <arnd@...db.de>, <linux-kernel@...r.kernel.org>,
        <suzhuangluan@...ilicon.com>, <dan.zhao@...ilicon.com>
Subject: Re: [PATCH RFC] random: fix syzkaller fuzzer test int overflow

Hi Ted,

On 2017/10/24 18:25, Theodore Ts'o wrote:
> On Tue, Oct 24, 2017 at 11:09:27AM +0200, Greg KH wrote:
>> On Tue, Oct 24, 2017 at 03:44:17PM +0800, Chen Feng wrote:
>>> [pid:11940,cpu6,syz-executor][flp_ioctl]cmd[0x1]
>>> Restart is not permit
>>> =================================================================
>>> UBSAN: Undefined behaviour in
>>> kernel/linux-4.4/drivers/char/random.c:676:19
>>> signed integer overflow:
>>> 2147483645 + 268435455 cannot be represented in type 'int'
>>> CPU: 4 PID: 11941 Comm: syz-executor Not tainted 4.4.76+ #2
>>
>> Does this also happen on 4.14-rc6?
> 
> No.  It was fixed in 4.8, by commit 86a574de4590: "random: strengthen
> input validation for RNDADDTOENTCNT".


I see my kernel has already merged this patch. So I don't think this patch
can resolve the issue above.

	-feng
> 
> 						- Ted
> 
> .
>