After *trying* to follow the discussion on ...
https://marc.info/?l=linux-kernel&m=154554485324143&w=2
[PATCH] net: core: Fix Spectre v1 vulnerability
... I'm still not sure whether af_can.c needs this enhancement or not.
Just waiting for the end of the discussion :-)
Thanks to the experts!
Oliver
On 12/21/18 10:22 PM, Gustavo A. R. Silva wrote:
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@xxxxxxxxxxxxxx>
---
net/can/af_can.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/net/can/af_can.c b/net/can/af_can.c
index 1684ba5b51eb..cade7250c6d4 100644
--- a/net/can/af_can.c
+++ b/net/can/af_can.c
@@ -59,6 +59,7 @@
#include <linux/can/core.h>
#include <linux/can/skb.h>
#include <linux/ratelimit.h>
+#include <linux/nospec.h>
#include <net/net_namespace.h>
#include <net/sock.h>
@@ -136,6 +137,7 @@ static int can_create(struct net *net, struct socket *sock, int protocol,
if (protocol < 0 || protocol >= CAN_NPROTO)
return -EINVAL;
+ protocol = array_index_nospec(protocol, CAN_NPROTO);
cp = can_get_proto(protocol);
