Re: Heap overflow vulnerabilities in network implementation of barebox

[Sascha Hauer <s.hauer@pengutronix.de>]

Hi,

On Thu, May 23, 2024 at 06:51:01PM +0200, jianqiang wang wrote:
> Dear Barebox devlopers,
> 
> I found several heap overflow vulnerabilities in Barebox.
> 
> The Barebox implementation assumes that the network packet received is
> less than PKTSIZE, that is 1536 bytes. For example, the /net/net.c
> file ping_reply function assumes that the packet received is 1536
> bytes and allocates a 1536 bytes buffer then copies the packet data
> into the buffer.
> 
> However, in the driver layer, it lacks a proper check of the packet length.
> For example, in drivers/net/cs8900.c cs8900_probe function, it
> allocates a PKTSIZE buffer and assigns it to rx_buf. In cs8900_recv
> function, the length is read from the device register:
> 
> len = readw(priv->regs + CS8900_RTDATA0);
> 
> After that, the data is read from the register in a loop without a
> boundary check.
> The same vulnerability happens to the following drivers:
> 
> drivers/net/ks8851_mll.c function ks8851_rx_frame, it only and the
> packet length with RXFHBCR_CNT_MASK (4095 bytes,) which is not
> consistent with the upper layer length check.
> 
> drivers/net/liteeth.c function liteeth_eth_rx, It checks if the length
> is larger than 2048 which is inconsistent with the upper layer.
> 
> drivers/net/smc911x.c function smc911x_eth_rx. The packet length is
> read from the register without checking.
> 
> It would be good to add a proper and consistent boundary check for
> these drivers otherwise it will lead to potential heap overflow
> vulnerability.

Thanks for noting this. I've just sent a series fixing the drivers you
explicitly mentioned. Additionally I have checked a few other drivers
and it seems at least the smc91111 driver has this issue as well. Are
you aware of other drivers?

Sascha

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