From: Nikolay Aleksandrov nikolay@cumulusnetworks.com
commit 3a20773beeeeadec41477a5ba872175b778ff752 upstream.
Since nl_groups is a u32 we can't bind more groups via ->bind (netlink_bind) call, but netlink has supported more groups via setsockopt() for a long time and thus nlk->ngroups could be over 32. Recently I added support for per-vlan notifications and increased the groups to 33 for NETLINK_ROUTE which exposed an old bug in the netlink_bind() code causing out-of-bounds access on archs where unsigned long is 32 bits via test_bit() on a local variable. Fix this by capping the maximum groups in netlink_bind() to BITS_PER_TYPE(u32), effectively capping them at 32 which is the minimum of allocated groups and the maximum groups which can be bound via netlink_bind().
CC: Christophe Leroy christophe.leroy@c-s.fr CC: Richard Guy Briggs rgb@redhat.com Fixes: 4f520900522f ("netlink: have netlink per-protocol bind function return an error code.") Reported-by: Erhard F. erhard_f@mailbox.org Signed-off-by: Nikolay Aleksandrov nikolay@cumulusnetworks.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/netlink/af_netlink.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
--- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -1029,7 +1029,8 @@ static int netlink_bind(struct socket *s if (nlk->netlink_bind && groups) { int group;
- for (group = 0; group < nlk->ngroups; group++) { + /* nl_groups is a u32, so cap the maximum groups we can bind */ + for (group = 0; group < BITS_PER_TYPE(u32); group++) { if (!test_bit(group, &groups)) continue; err = nlk->netlink_bind(net, group + 1); @@ -1048,7 +1049,7 @@ static int netlink_bind(struct socket *s netlink_insert(sk, nladdr->nl_pid) : netlink_autobind(sock); if (err) { - netlink_undo_bind(nlk->ngroups, groups, sk); + netlink_undo_bind(BITS_PER_TYPE(u32), groups, sk); goto unlock; } }