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From: Greg KH <gregkh@linuxfoundation.org>
To: Kyungtae Kim <kt0755@gmail.com>
Cc: jslaby@suse.com, slyfox@gentoo.org,
	Dmitry Torokhov <dmitry.torokhov@gmail.com>,
	rei4dan@gmail.com, Dave Tian <dave.jing.tian@gmail.com>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: UBSAN: Undefined behaviour in drivers/tty/vt/keyboard.c
Date: Mon, 23 Mar 2020 07:46:16 +0100
Message-ID: <20200323064616.GB129571@kroah.com> (raw)
In-Reply-To: <CAEAjamv3wT4aqF0y1_PHG_=cbzH-ATsP6TiV5Zt5Qc+ACVnOPw@mail.gmail.com>

On Sun, Mar 22, 2020 at 11:34:01PM -0400, Kyungtae Kim wrote:
> We report a bug (in linux-5.5.11) found by FuzzUSB (modified version
> of syzkaller)
> 
> Seems the variable "npadch" has a very large value (i.e., 333333333)
> as a result of multiple executions of the function "k_ascii" (keyboard.c:888)
> while the variable "base" has 10.
> So their multiplication at line 888 in "k_ascii" will become
> larger than the max of type int, causing such an integer overflow.
> 
> I believe this can be solved by checking for overflow ahead of operations
> e.g., using check_mul_overflow().
> 
> kernel config: https://kt0755.github.io/etc/config_v5.5.11

Great, can you send a patch for this?

thanks,

greg k-h

  reply index

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-23  3:34 Kyungtae Kim
2020-03-23  6:46 ` Greg KH [this message]
2020-03-23 20:44   ` Kyungtae Kim
2020-03-24 12:12     ` Greg KH
2020-03-26 14:51       ` Kyungtae Kim

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