net: atm: Fix potential Spectre v1 vulnerabilities
authorGustavo A. R. Silva <gustavo@embeddedor.com>
Mon, 15 Apr 2019 20:57:23 +0000 (15:57 -0500)
committerDavid S. Miller <davem@davemloft.net>
Wed, 17 Apr 2019 04:01:45 +0000 (21:01 -0700)
commit899537b73557aafbdd11050b501cf54b4f5c45af
treefb231860e44e0e39982d5bf475c569b79bce1003
parentad910c7c01269f229a97c335f2dc669fff750f65
net: atm: Fix potential Spectre v1 vulnerabilities

arg is 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:715 lec_mcast_attach() warn: potential spectre issue 'dev_lec' [r] (local cap)

Fix this by sanitizing arg before using it to index dev_lec.

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://lore.kernel.org/lkml/20180423164740.GY17484@dhcp22.suse.cz/

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/atm/lec.c