Re: [PATCH] ipv6: addrlabel: fix infoleak when sending struct ifaddrlblmsg to network

[syzbot]

> On 11/4/22 4:32 AM, Alexander Potapenko wrote:
>> 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>
>> ---
>>  net/ipv6/addrlabel.c | 1 +
>>  1 file changed, 1 insertion(+)
>> 
>
> Reviewed-by: David Ahern <dsahern@xxxxxxxxxx>
>
>

I see the command but can't find the corresponding bug.
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