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

From: Dmitry Safonov <redacted>
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 <redacted>
Signed-off-by: Dmitry Safonov <redacted>

Applied and queued up for -stable.