From 3044b16e7c6fe5d24b1cdbcf1bd0a9d92d1ebd81 Mon Sep 17 00:00:00 2001
From: valis <sec@valis.email>
Date: Sat, 29 Jul 2023 08:32:00 -0400
Subject: [PATCH 1/3] net/sched: cls_u32: No longer copy tcf_result on update
 to avoid use-after-free
Git-commit: 3044b16e7c6fe5d24b1cdbcf1bd0a9d92d1ebd81
Patch-mainline: v6.5-rc5
References: bsc#1214149 CVE-2023-4128

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 <sec@valis.email>
Reported-by: M A Ramdhan <ramdhan@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/20230729123202.72406-2-jhs@mojatatu.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Vasant Karasulli <vkarasulli@suse.de>

---
 net/sched/cls_u32.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c
index 907e58841fe8..da4c179a4d41 100644
--- a/net/sched/cls_u32.c
+++ b/net/sched/cls_u32.c
@@ -834,7 +834,6 @@ static struct tc_u_knode *u32_init_knode
 	new->ifindex = n->ifindex;
 #endif
 	new->fshift = n->fshift;
-	new->res = n->res;
 	new->flags = n->flags;
 	RCU_INIT_POINTER(new->ht_down, ht);
 
--
2.34.1