From: valis Date: Sat, 29 Jul 2023 12:32:00 +0000 (-0400) Subject: net/sched: cls_u32: No longer copy tcf_result on update to avoid use-after-free X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=3044b16e7c6fe5d24b1cdbcf1bd0a9d92d1ebd81;p=linux.git 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 Reported-by: M A Ramdhan Signed-off-by: valis Signed-off-by: Jamal Hadi Salim Reviewed-by: Victor Nogueira Reviewed-by: Pedro Tammela Reviewed-by: M A Ramdhan Link: https://lore.kernel.org/r/20230729123202.72406-2-jhs@mojatatu.com Signed-off-by: Jakub Kicinski --- diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c index 907e58841fe80..da4c179a4d418 100644 --- a/net/sched/cls_u32.c +++ b/net/sched/cls_u32.c @@ -826,7 +826,6 @@ static struct tc_u_knode *u32_init_knode(struct net *net, struct tcf_proto *tp, new->ifindex = n->ifindex; new->fshift = n->fshift; - new->res = n->res; new->flags = n->flags; RCU_INIT_POINTER(new->ht_down, ht);