CVE-2024-35960

In the Linux kernel, the following vulnerability has been resolved:
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.