4.20-stable review patch. If anyone has any objections, please let me know. ------------------ From: "Gustavo A. R. Silva" <gustavo@xxxxxxxxxxxxxx> [ 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@xxxxxxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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]);
