From a5928d68418768e3e7ed9c75039060c1e70e047e Mon Sep 17 00:00:00 2001 From: Dmitry Safonov Date: Sun, 5 Aug 2018 01:35:53 +0100 Subject: [PATCH] netlink: Don't shift on 64 for ngroups commit 91874ecf32e41b5d86a4cb9d60e0bee50d828058 upstream. It's legal to have 64 groups for netlink_sock. As user-supplied nladdr->nl_groups is __u32, it's possible to subscribe only to first 32 groups. The check for correctness of .bind() userspace supplied parameter is done by applying mask made from ngroups shift. Which broke Android as they have 64 groups and the shift for mask resulted in an overflow. Fixes: 61f4b23769f0 ("netlink: Don't shift with UB on nlk->ngroups") Cc: "David S. Miller" Cc: Herbert Xu Cc: Steffen Klassert Cc: netdev@vger.kernel.org Cc: stable@vger.kernel.org Reported-and-Tested-by: Nathan Chancellor Signed-off-by: Dmitry Safonov Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/netlink/af_netlink.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index 87c25918c073..bf292010760a 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -988,8 +988,8 @@ static int netlink_bind(struct socket *sock, struct sockaddr *addr, if (nlk->ngroups == 0) groups = 0; - else - groups &= (1ULL << nlk->ngroups) - 1; + else if (nlk->ngroups < 8*sizeof(groups)) + groups &= (1UL << nlk->ngroups) - 1; bound = nlk->bound; if (bound) {