Re: [PATCH] net: atm: Fix potential Spectre v1

[David Miller]

From: "Gustavo A. R. Silva" <gustavo@xxxxxxxxxxxxxx>
Date: Thu, 3 May 2018 13:45:58 -0500

> ioc_data.dev_num can be controlled by user-space, hence leading to
> a potential exploitation of the Spectre variant 1 vulnerability.
> 
> This issue was detected with the help of Smatch:
> net/atm/lec.c:702 lec_vcc_attach() warn: potential spectre issue
> 'dev_lec'
> 
> Fix this by sanitizing ioc_data.dev_num before using it to index
> dev_lec. Also, notice that there is another instance in which array
> dev_lec is being indexed using ioc_data.dev_num at line 705:
> lec_vcc_added(netdev_priv(dev_lec[ioc_data.dev_num]),
> 
> Notice that given that speculation windows are large, the policy is
> to kill the speculation on the first load and not worry if it can be
> completed with a dependent load/store [1].
> 
> [1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2
> 
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>

Applied and queued up for -stable, thanks.