can: af_can: Fix Spectre v1 vulnerability
authorGustavo A. R. Silva <gustavo@embeddedor.com>
Fri, 21 Dec 2018 21:22:29 +0000 (15:22 -0600)
committerDavid S. Miller <davem@davemloft.net>
Sun, 23 Dec 2018 02:41:58 +0000 (18:41 -0800)
commita3ac5817ffe8f81dbe6be1522b499b48bc322e3a
tree43411ab4065691f005e57aae92d736debc393989
parent6b8d95f1795c42161dc0984b6863e95d6acf24ed
can: af_can: 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/can/af_can.c:115 can_get_proto() warn: potential spectre issue 'proto_tab' [w]

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/can/af_can.c