On 10/29/21 19:26, [email protected] wrote:
> From: Numan Siddique <[email protected]>
> 
> xlate_check_pkt_larger() sets ctx->exit to 'true' at the end
> causing the translation to stop. This results in incomplete
> datapath rules.
> 
> For example, for the below OF rules configured on a bridge,
> 
> table=0,in_port=1 
> actions=load:0x1->NXM_NX_REG1[[]],resubmit(,1),load:0x2->NXM_NX_REG1[[]],resubmit(,1),load:0x3->NXM_NX_REG1[[]],resubmit(,1)
> table=1,in_port=1,reg1=0x1 
> actions=check_pkt_larger(200)->NXM_NX_REG0[[0]],resubmit(,4)
> table=1,in_port=1,reg1=0x2 actions=output:2
> table=1,in_port=1,reg1=0x3 actions=output:4
> table=4,in_port=1 actions=output:3
> 
> the datapath flow should be
> 
> check_pkt_len(size=200,gt(3),le(3)),2,4
> 
> But right now it is:
> 
> check_pkt_len(size=200,gt(3),le(3))
> 
> Actions after the first resubmit(,1) in the first flow in table 0
> are never applied.  This patch fixes this issue.
> 
> Fixes: 5b34f8fc3b38 ("Add a new OVS action check_pkt_larger")
> Reported-at: https://bugzilla.redhat.com/show_bug.cgi?id=2018365
> Reported-by: Ihar Hrachyshka <[email protected]>
> Signed-off-by: Numan Siddique <[email protected]>
> ---
>  ofproto/ofproto-dpif-xlate.c |  9 ++++++++-
>  tests/ofproto-dpif.at        | 17 +++++++++++++++++
>  2 files changed, 25 insertions(+), 1 deletion(-)
> 
> diff --git a/ofproto/ofproto-dpif-xlate.c b/ofproto/ofproto-dpif-xlate.c
> index 9d336bc6a6..e22a39a9f4 100644
> --- a/ofproto/ofproto-dpif-xlate.c
> +++ b/ofproto/ofproto-dpif-xlate.c
> @@ -6371,6 +6371,7 @@ xlate_check_pkt_larger(struct xlate_ctx *ctx,
>       * then ctx->exit would be true. Reset to false so that we can
>       * do flow translation for 'IF_LESS_EQUAL' case. finish_freezing()
>       * would have taken care of Undoing the changes done for freeze. */
> +    bool old_exit = ctx->exit;
>      ctx->exit = false;
>  
>      offset_attr = nl_msg_start_nested(
> @@ -6395,7 +6396,7 @@ xlate_check_pkt_larger(struct xlate_ctx *ctx,
>      ctx->was_mpls = old_was_mpls;
>      ctx->conntracked = old_conntracked;
>      ctx->xin->flow = old_flow;
> -    ctx->exit = true;
> +    ctx->exit = old_exit;
>  }
>  
>  static void
> @@ -7192,6 +7193,12 @@ do_xlate_actions(const struct ofpact *ofpacts, size_t 
> ofpacts_len,
>                                                               ofpacts_len);
>              xlate_check_pkt_larger(ctx, ofpact_get_CHECK_PKT_LARGER(a),
>                                     remaining_acts, remaining_acts_len);
> +            if (ctx->xbridge->support.check_pkt_len) {
> +                /* If datapath supports check_pkt_len, then
> +                 * xlate_check_pkt_larger() does the translation for the
> +                 * ofpacts following 'a'. */
> +                a = ofpact_end(ofpacts, ofpacts_len);

Hi, Numan.

Looks like this change triggers heap-buffer-overflow.
See the ASAN report in ovsrobot's run for details.

Best regards, Ilya Maximets.
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