Patch "net/sched: cls_u32: No longer copy tcf_result on update to avoid use-after-free" has been added to the 4.14-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

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

to the 4.14-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     net-sched-cls_u32-no-longer-copy-tcf_result-on-updat.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit e7de86487dd0baf4a9d2ec914e7e2f13e03bca39
Author: valis <sec@valis.email>
Date:   Sat Jul 29 08:32:00 2023 -0400

    net/sched: cls_u32: No longer copy tcf_result on update to avoid use-after-free
    
    [ Upstream commit 3044b16e7c6fe5d24b1cdbcf1bd0a9d92d1ebd81 ]
    
    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@xxxxxxxxxxx>
    Signed-off-by: valis <sec@valis.email>
    Signed-off-by: Jamal Hadi Salim <jhs@xxxxxxxxxxxx>
    Reviewed-by: Victor Nogueira <victor@xxxxxxxxxxxx>
    Reviewed-by: Pedro Tammela <pctammela@xxxxxxxxxxxx>
    Reviewed-by: M A Ramdhan <ramdhan@xxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20230729123202.72406-2-jhs@xxxxxxxxxxxx
    Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c
index a4e01220a53a1..8a2fc40ae8402 100644
--- a/net/sched/cls_u32.c
+++ b/net/sched/cls_u32.c
@@ -870,7 +870,6 @@ static struct tc_u_knode *u32_init_knode(struct tcf_proto *tp,
 	new->ifindex = n->ifindex;
 #endif
 	new->fshift = n->fshift;
-	new->res = n->res;
 	new->flags = n->flags;
 	RCU_INIT_POINTER(new->ht_down, n->ht_down);