net/mlx5e: CT: Fix null-ptr-deref in add rule err flow

In error flow of mlx5_tc_ct_entry_add_rule(), in case ct_rule_add()
callback returns error, zone_rule->attr is used uninitiated. Fix it to
use attr which has the needed pointer value.

Kernel log:
 BUG: kernel NULL pointer dereference, address: 0000000000000110
 RIP: 0010:mlx5_tc_ct_entry_add_rule+0x2b1/0x2f0 [mlx5_core]
…
 Call Trace:
  <TASK>
  ? __die+0x20/0x70
  ? page_fault_oops+0x150/0x3e0
  ? exc_page_fault+0x74/0x140
  ? asm_exc_page_fault+0x22/0x30
  ? mlx5_tc_ct_entry_add_rule+0x2b1/0x2f0 [mlx5_core]
  ? mlx5_tc_ct_entry_add_rule+0x1d5/0x2f0 [mlx5_core]
  mlx5_tc_ct_block_flow_offload+0xc6a/0xf90 [mlx5_core]
  ? nf_flow_offload_tuple+0xd8/0x190 [nf_flow_table]
  nf_flow_offload_tuple+0xd8/0x190 [nf_flow_table]
  flow_offload_work_handler+0x142/0x320 [nf_flow_table]
  ? finish_task_switch.isra.0+0x15b/0x2b0
  process_one_work+0x16c/0x320
  worker_thread+0x28c/0x3a0
  ? __pfx_worker_thread+0x10/0x10
  kthread+0xb8/0xf0
  ? __pfx_kthread+0x10/0x10
  ret_from_fork+0x2d/0x50
  ? __pfx_kthread+0x10/0x10
  ret_from_fork_asm+0x1a/0x30
  </TASK>

Fixes: 7fac5c2 ("net/mlx5: CT: Avoid reusing modify header context for natted entries")
Signed-off-by: Moshe Shemesh <[email protected]>
Reviewed-by: Cosmin Ratiu <[email protected]>
Reviewed-by: Yevgeny Kliteynik <[email protected]>
Signed-off-by: Tariq Toukan <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: mosheshemesh2

drivers/net/ethernet/mellanox/mlx5/core/en/tc_ct.c

@@ -866,7 +866,7 @@ mlx5_tc_ct_entry_add_rule(struct mlx5_tc_ct_priv *ct_priv,
 	return 0;
 
 err_rule:
-	mlx5_tc_ct_entry_destroy_mod_hdr(ct_priv, zone_rule->attr, zone_rule->mh);
+	mlx5_tc_ct_entry_destroy_mod_hdr(ct_priv, attr, zone_rule->mh);
 	mlx5_put_label_mapping(ct_priv, attr->ct_attr.ct_labels_id);
 err_mod_hdr:
 	kfree(attr);