[ovs-dev] [PATCH] ofproto-dpif-upcall: Fix using uninitialized upcall hash.

Tonghao Zhang xiangxia.m.yue at gmail.com
Sat Jan 4 03:16:27 UTC 2020


On Sat, Jan 4, 2020 at 8:16 AM Ilya Maximets <i.maximets at ovn.org> wrote:
>
> upcalls are allocated on stack and 'hash' field must be initialized
> regardless of attribute existence because it will be used later.
>
>  Conditional jump or move depends on uninitialised value(s)
>     at 0xFA74A7: dpif_netlink_encode_execute (dpif-netlink.c:1828)
>     by 0xFA6DE8: dpif_netlink_operate__ (dpif-netlink.c:1906)
>     by 0xFA612F: dpif_netlink_operate_chunks (dpif-netlink.c:2219)
>     by 0xFA0E36: dpif_netlink_operate (dpif-netlink.c:2275)
>     by 0xE5AFAC: dpif_operate (dpif.c:1376)
>     by 0xDF3922: handle_upcalls (ofproto-dpif-upcall.c:1615)
>     by 0xDF269B: recv_upcalls (ofproto-dpif-upcall.c:857)
>     by 0xDF1C49: udpif_upcall_handler (ofproto-dpif-upcall.c:759)
>     by 0xF3A3FE: ovsthread_wrapper (ovs-thread.c:383)
>     by 0x565F6DA: start_thread (pthread_create.c:463)
>     by 0x615988E: clone (clone.S:95)
>   Uninitialised value was created by a stack allocation
>     at 0xDF2258: recv_upcalls (ofproto-dpif-upcall.c:773)
>
> Fixes: 0442bfb11d6c ("ofproto-dpif-upcall: Echo HASH attribute back to datapath.")
> Signed-off-by: Ilya Maximets <i.maximets at ovn.org>
> ---
>  ofproto/ofproto-dpif-upcall.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/ofproto/ofproto-dpif-upcall.c b/ofproto/ofproto-dpif-upcall.c
> index aac0554af..409286ab1 100644
> --- a/ofproto/ofproto-dpif-upcall.c
> +++ b/ofproto/ofproto-dpif-upcall.c
> @@ -786,6 +786,7 @@ recv_upcalls(struct handler *handler)
>          struct upcall *upcall = &upcalls[n_upcalls];
>          struct flow *flow = &flows[n_upcalls];
>          unsigned int mru = 0;
> +        uint64_t hash = 0;
>          int error;
>
>          ofpbuf_use_stub(recv_buf, recv_stubs[n_upcalls],
> @@ -806,7 +807,7 @@ recv_upcalls(struct handler *handler)
>          }
>
>          if (dupcall->hash) {
> -            upcall->hash = nl_attr_get_u64(dupcall->hash);
> +            hash = nl_attr_get_u64(dupcall->hash);
>          }
>
>          error = upcall_receive(upcall, udpif->backer, &dupcall->packet,
> @@ -830,6 +831,7 @@ recv_upcalls(struct handler *handler)
>          upcall->key = dupcall->key;
>          upcall->key_len = dupcall->key_len;
>          upcall->ufid = &dupcall->ufid;
> +        upcall->hash = hash;
>
>          upcall->out_tun_key = dupcall->out_tun_key;
>          upcall->actions = dupcall->actions;
> --
> 2.17.1
>
Acked-by: Tonghao Zhang <xiangxia.m.yue at gmail.com>


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