phonet: af_phonet: Fix Spectre v1 vulnerability
authorGustavo A. R. Silva <gustavo@embeddedor.com>
Fri, 21 Dec 2018 21:41:17 +0000 (15:41 -0600)
committerDavid S. Miller <davem@davemloft.net>
Sat, 22 Dec 2018 23:08:15 +0000 (15:08 -0800)
commitd686026b1e6ed4ea27d630d8f54f9a694db088b2
treed7bd2f44af64de4131d4dcfb161f6d6c9e18bcc1
parent50d5258634aee2e62832aa086d2fb0de00e72b91
phonet: af_phonet: Fix Spectre v1 vulnerability

protocol 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/phonet/af_phonet.c:48 phonet_proto_get() warn: potential spectre issue 'proto_tab' [w] (local cap)

Fix this by sanitizing protocol before using it to index proto_tab.

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@embeddedor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/phonet/af_phonet.c