net/mlx5: Properly link new fs rules into the tree

JIRA: https://issues.redhat.com/browse/RHEL-37422
CVE: CVE-2024-35960

commit 7c6782ad4911cbee874e85630226ed389ff2e453
Author: Cosmin Ratiu cratiu@nvidia.com
Date: Tue Apr 9 22:08:12 2024 +0300

net/mlx5: Properly link new fs rules into the tree  

Previously, add_rule_fg would only add newly created rules from the  
handle into the tree when they had a refcount of 1. On the other hand,  
create_flow_handle tries hard to find and reference already existing  
identical rules instead of creating new ones.  

These two behaviors can result in a situation where create_flow_handle  
1) creates a new rule and references it, then  
2) in a subsequent step during the same handle creation references it  
   again,  
resulting in a rule with a refcount of 2 that is not linked into the  
tree, will have a NULL parent and root and will result in a crash when  
the flow group is deleted because del_sw_hw_rule, invoked on rule  
deletion, assumes node->parent is != NULL.  

This happened in the wild, due to another bug related to incorrect  
handling of duplicate pkt_reformat ids, which lead to the code in  
create_flow_handle incorrectly referencing a just-added rule in the same  
flow handle, resulting in the problem described above. Full details are  
at [1].  

This patch changes add_rule_fg to add new rules without parents into  
the tree, properly initializing them and avoiding the crash. This makes  
it more consistent with how rules are added to an FTE in  
create_flow_handle.  

Fixes: 74491de93712 ("net/mlx5: Add multi dest support")  
Link: https://lore.kernel.org/netdev/ea5264d6-6b55-4449-a602-214c6f509c1e@163.com/T/#u [1]  
Signed-off-by: Cosmin Ratiu <cratiu@nvidia.com>  
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>  
Reviewed-by: Mark Bloch <mbloch@nvidia.com>  
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>  
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>  
Link: https://lore.kernel.org/r/20240409190820.227554-5-tariqt@nvidia.com  
Signed-off-by: Jakub Kicinski <kuba@kernel.org>  

Signed-off-by: Kamal Heib kheib@redhat.com