Commit 91874ecf authored Aug 05, 2018 by Dmitry Safonov Committed by David S. Miller Aug 04, 2018

netlink: Don't shift on 64 for ngroups



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: 61f4b237 ("netlink: Don't shift with UB on nlk->ngroups")
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: netdev@vger.kernel.org
Cc: stable@vger.kernel.org
Reported-and-Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 5dbfb6ec

net/netlink/af_netlink.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -1013,8 +1013,8 @@ 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) {

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