From: Greg KH <gregkh@linuxfoundation.org>
To: Len Baker <len.baker@gmx.com>
Cc: Yan-Hsuan Chuang <tony0620emma@gmail.com>,
Kalle Valo <kvalo@codeaurora.org>,
"David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Stanislaw Gruszka <sgruszka@redhat.com>,
Brian Norris <briannorris@chromium.org>,
Pkshih <pkshih@realtek.com>,
linux-wireless@vger.kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH v2] rtw88: Fix out-of-bounds write
Date: Fri, 16 Jul 2021 19:20:48 +0200 [thread overview]
Message-ID: <YPG/8F7yYLm3vAlG@kroah.com> (raw)
In-Reply-To: <20210716155311.5570-1-len.baker@gmx.com>
On Fri, Jul 16, 2021 at 05:53:11PM +0200, Len Baker wrote:
> In the rtw_pci_init_rx_ring function the "if (len > TRX_BD_IDX_MASK)"
> statement guarantees that len is less than or equal to GENMASK(11, 0) or
> in other words that len is less than or equal to 4095. However the
> rx_ring->buf has a size of RTK_MAX_RX_DESC_NUM (defined as 512). This
> way it is possible an out-of-bounds write in the for statement due to
> the i variable can exceed the rx_ring->buff size.
>
> However, this overflow never happens due to the rtw_pci_init_rx_ring is
> only ever called with a fixed constant of RTK_MAX_RX_DESC_NUM. But it is
> better to be defensive in this case and add a new check to avoid
> overflows if this function is called in a future with a value greater
> than 512.
If this can never happen, then no, this is not needed. Why would you
check twice for the same thing?
thanks,
greg k-h
next prev parent reply other threads:[~2021-07-16 17:22 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-16 15:53 [PATCH v2] rtw88: Fix out-of-bounds write Len Baker
2021-07-16 16:58 ` Brian Norris
2021-07-16 17:20 ` Greg KH [this message]
2021-07-17 13:33 ` Len Baker
2021-07-17 17:33 ` Greg KH
2021-07-18 7:53 ` Len Baker
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