From 61f4b23769f0cc72ae62c9a81cf08f0397d40da8 Mon Sep 17 00:00:00 2001 From: Dmitry Safonov Date: Mon, 30 Jul 2018 18:32:36 +0100 Subject: [PATCH] netlink: Don't shift with UB on nlk->ngroups On i386 nlk->ngroups might be 32 or 0. Which leads to UB, resulting in hang during boot. Check for 0 ngroups and use (unsigned long long) as a type to shift. Fixes: 7acf9d4237c4 ("netlink: Do not subscribe to non-existent groups"). Reported-by: kernel test robot Signed-off-by: Dmitry Safonov Signed-off-by: David S. Miller --- net/netlink/af_netlink.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index ac805caed2e2..7d860a22e5fb 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -1008,7 +1008,11 @@ static int netlink_bind(struct socket *sock, struct sockaddr *addr, if (err) return err; } - groups &= (1UL << nlk->ngroups) - 1; + + if (nlk->ngroups == 0) + groups = 0; + else + groups &= (1ULL << nlk->ngroups) - 1; bound = nlk->bound; if (bound) {