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

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Date:   Tue, 24 Oct 2017 06:25:28 -0400
From:   Theodore Ts'o <tytso@....edu>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     Chen Feng <puck.chen@...ilicon.com>, 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

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".

						- Ted