net/sched: cls_u32: No longer copy tcf_result on update to avoid use-after-free

When u32_change() is called on an existing filter, the whole
tcf_result struct is always copied into the new instance of the filter.

This causes a problem when updating a filter bound to a class,
as tcf_unbind_filter() is always called on the old instance in the
success path, decreasing filter_cnt of the still referenced class
and allowing it to be deleted, leading to a use-after-free.

Fix this by no longer copying the tcf_result struct from the old filter.

Fixes: de5df63228fc ("net: sched: cls_u32 changes to knode must appear atomic to readers")
Reported-by: valis <[email protected]>
Reported-by: M A Ramdhan <[email protected]>
Signed-off-by: valis <[email protected]>
Signed-off-by: Jamal Hadi Salim <[email protected]>
Reviewed-by: Victor Nogueira <[email protected]>
Reviewed-by: Pedro Tammela <[email protected]>
Reviewed-by: M A Ramdhan <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

0 files changed, 0 insertions, 0 deletions