Patch "net/sched: cls_fw: No longer copy tcf_result on update to avoid use-after-free" has been added to the 5.15-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_fw: No longer copy tcf_result on update to avoid use-after-free

to the 5.15-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_fw-no-longer-copy-tcf_result-on-update.patch
and it can be found in the queue-5.15 subdirectory.

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



commit 708fc9906a9f632ac4e049dc46d70892502cd3a6
Author: valis <sec@valis.email>
Date:   Sat Jul 29 08:32:01 2023 -0400

    net/sched: cls_fw: No longer copy tcf_result on update to avoid use-after-free
    
    [ Upstream commit 76e42ae831991c828cffa8c37736ebfb831ad5ec ]
    
    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@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/20230729123202.72406-3-jhs@xxxxxxxxxxxx
    Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/net/sched/cls_fw.c b/net/sched/cls_fw.c
index ea52c320f67c4..a2f53aee39097 100644
--- a/net/sched/cls_fw.c
+++ b/net/sched/cls_fw.c
@@ -265,7 +265,6 @@ static int fw_change(struct net *net, struct sk_buff *in_skb,
 			return -ENOBUFS;
 
 		fnew->id = f->id;
-		fnew->res = f->res;
 		fnew->ifindex = f->ifindex;
 		fnew->tp = f->tp;