net/sched: cls_fw: No longer copy tcf_result on update to avoid use-after-free
authorvalis <sec@valis.email>
Sat, 29 Jul 2023 12:32:01 +0000 (08:32 -0400)
committerJakub Kicinski <kuba@kernel.org>
Tue, 1 Aug 2023 03:10:36 +0000 (20:10 -0700)
commit76e42ae831991c828cffa8c37736ebfb831ad5ec
treea4063cc30b4cb2f170728aa91a793d58e49e35d3
parent3044b16e7c6fe5d24b1cdbcf1bd0a9d92d1ebd81
net/sched: cls_fw: No longer copy tcf_result on update to avoid use-after-free

When fw_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: e35a8ee5993b ("net: sched: fw use RCU")
Reported-by: valis <sec@valis.email>
Reported-by: Bing-Jhong Billy Jheng <billy@starlabs.sg>
Signed-off-by: valis <sec@valis.email>
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Reviewed-by: Victor Nogueira <victor@mojatatu.com>
Reviewed-by: Pedro Tammela <pctammela@mojatatu.com>
Reviewed-by: M A Ramdhan <ramdhan@starlabs.sg>
Link: https://lore.kernel.org/r/20230729123202.72406-3-jhs@mojatatu.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
net/sched/cls_fw.c