4.20-stable review patch. If anyone has any objections, please let me know.
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From: "Gustavo A. R. Silva" gustavo@embeddedor.com
[ Upstream commit d686026b1e6ed4ea27d630d8f54f9a694db088b2 ]
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/phonet/af_phonet.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/net/phonet/af_phonet.c +++ b/net/phonet/af_phonet.c @@ -34,6 +34,8 @@ #include <net/phonet/phonet.h> #include <net/phonet/pn_dev.h>
+#include <linux/nospec.h> + /* Transport protocol registration */ static const struct phonet_protocol *proto_tab[PHONET_NPROTO] __read_mostly;
@@ -43,6 +45,7 @@ static const struct phonet_protocol *pho
if (protocol >= PHONET_NPROTO) return NULL; + protocol = array_index_nospec(protocol, PHONET_NPROTO);
rcu_read_lock(); pp = rcu_dereference(proto_tab[protocol]);