> From: Alexander Potapenko <glider@xxxxxxxxxx> > > [ Upstream commit c23fb2c82267638f9d206cb96bb93e1f93ad7828 ] > > When copying a `struct ifaddrlblmsg` to the network, __ifal_reserved > remained uninitialized, resulting in a 1-byte infoleak: > > BUG: KMSAN: kernel-network-infoleak in __netdev_start_xmit ./include/linux/netdevice.h:4841 > __netdev_start_xmit ./include/linux/netdevice.h:4841 > netdev_start_xmit ./include/linux/netdevice.h:4857 > xmit_one net/core/dev.c:3590 > dev_hard_start_xmit+0x1dc/0x800 net/core/dev.c:3606 > __dev_queue_xmit+0x17e8/0x4350 net/core/dev.c:4256 > dev_queue_xmit ./include/linux/netdevice.h:3009 > __netlink_deliver_tap_skb net/netlink/af_netlink.c:307 > __netlink_deliver_tap+0x728/0xad0 net/netlink/af_netlink.c:325 > netlink_deliver_tap net/netlink/af_netlink.c:338 > __netlink_sendskb net/netlink/af_netlink.c:1263 > netlink_sendskb+0x1d9/0x200 net/netlink/af_netlink.c:1272 > netlink_unicast+0x56d/0xf50 net/netlink/af_netlink.c:1360 > nlmsg_unicast ./include/net/netlink.h:1061 > rtnl_unicast+0x5a/0x80 net/core/rtnetlink.c:758 > ip6addrlbl_get+0xfad/0x10f0 net/ipv6/addrlabel.c:628 > rtnetlink_rcv_msg+0xb33/0x1570 net/core/rtnetlink.c:6082 > ... > Uninit was created at: > slab_post_alloc_hook+0x118/0xb00 mm/slab.h:742 > slab_alloc_node mm/slub.c:3398 > __kmem_cache_alloc_node+0x4f2/0x930 mm/slub.c:3437 > __do_kmalloc_node mm/slab_common.c:954 > __kmalloc_node_track_caller+0x117/0x3d0 mm/slab_common.c:975 > kmalloc_reserve net/core/skbuff.c:437 > __alloc_skb+0x27a/0xab0 net/core/skbuff.c:509 > alloc_skb ./include/linux/skbuff.h:1267 > nlmsg_new ./include/net/netlink.h:964 > ip6addrlbl_get+0x490/0x10f0 net/ipv6/addrlabel.c:608 > rtnetlink_rcv_msg+0xb33/0x1570 net/core/rtnetlink.c:6082 > netlink_rcv_skb+0x299/0x550 net/netlink/af_netlink.c:2540 > rtnetlink_rcv+0x26/0x30 net/core/rtnetlink.c:6109 > netlink_unicast_kernel net/netlink/af_netlink.c:1319 > netlink_unicast+0x9ab/0xf50 net/netlink/af_netlink.c:1345 > netlink_sendmsg+0xebc/0x10f0 net/netlink/af_netlink.c:1921 > ... > > This patch ensures that the reserved field is always initialized. > > Reported-by: syzbot+3553517af6020c4f2813f1003fe76ef3cbffe98d@xxxxxxxxxxxxxxxxxxxxxxxxx > Fixes: 2a8cc6c89039 ("[IPV6] ADDRCONF: Support RFC3484 configurable address selection policy table.") > Signed-off-by: Alexander Potapenko <glider@xxxxxxxxxx> > Reviewed-by: David Ahern <dsahern@xxxxxxxxxx> > Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> > --- > net/ipv6/addrlabel.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/net/ipv6/addrlabel.c b/net/ipv6/addrlabel.c > index 8a22486cf270..17ac45aa7194 100644 > --- a/net/ipv6/addrlabel.c > +++ b/net/ipv6/addrlabel.c > @@ -437,6 +437,7 @@ static void ip6addrlbl_putmsg(struct nlmsghdr *nlh, > { > struct ifaddrlblmsg *ifal = nlmsg_data(nlh); > ifal->ifal_family = AF_INET6; > + ifal->__ifal_reserved = 0; > ifal->ifal_prefixlen = prefixlen; > ifal->ifal_flags = 0; > ifal->ifal_index = ifindex; > -- > 2.35.1 > > > I see the command but can't find the corresponding bug. The email is sent to syzbot+HASH@xxxxxxxxxxxxxxxxxxxxxxxxx address but the HASH does not correspond to any known bug. Please double check the address.