Re: [PATCHv2] netlink: Don't shift on 64 for ngroups

From: Dmitry Safonov dima@arista.com Date: Sun, 5 Aug 2018 01:35:53 +0100

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") Reported-and-Tested-by: Nathan Chancellor natechancellor@gmail.com Signed-off-by: Dmitry Safonov dima@arista.com

Applied and queued up for -stable.