Re: [PATCH] ip6mr: Fix potential Spectre v1 vulnerability

[David Miller]

From: "Gustavo A. R. Silva" <gustavo@xxxxxxxxxxxxxx>
Date: Tue, 11 Dec 2018 14:10:08 -0600

> vr.mifi is indirectly 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/ipv6/ip6mr.c:1845 ip6mr_ioctl() warn: potential spectre issue 'mrt->vif_table' [r] (local cap)
> net/ipv6/ip6mr.c:1919 ip6mr_compat_ioctl() warn: potential spectre issue 'mrt->vif_table' [r] (local cap)
> 
> Fix this by sanitizing vr.mifi before using it to index mrt->vif_table'
> 
> 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
> 
> Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>

Applied and queued up for -stable.