> 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.
