4.9-stable review patch. If anyone has any objections, please let me know.
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From: Dmitry Safonov dima@arista.com
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" 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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/netlink/af_netlink.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -988,8 +988,8 @@ static int netlink_bind(struct socket *s
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) {