4.17-stable review patch. If anyone has any objections, please let me know.
------------------ From: Dmitry Safonov <[email protected]> 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" <[email protected]> Cc: Herbert Xu <[email protected]> Cc: Steffen Klassert <[email protected]> Cc: [email protected] Cc: [email protected] Reported-and-Tested-by: Nathan Chancellor <[email protected]> Signed-off-by: Dmitry Safonov <[email protected]> Signed-off-by: David S. Miller <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- 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 @@ -1013,8 +1013,8 @@ 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) {
