Commit fffd3058 authored Jul 30, 2018 by Dmitry Safonov Committed by Greg Kroah-Hartman Aug 03, 2018

netlink: Don't shift with UB on nlk->ngroups



[ Upstream commit 61f4b23769f0cc72ae62c9a81cf08f0397d40da8 ]

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 <rong.a.chen@intel.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent e208cda5

net/netlink/af_netlink.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -976,7 +976,11 @@ 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) {