From: valis sec@valis.email
[ 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@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 Signed-off-by: Sasha Levin sashal@kernel.org --- 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 0e3bb1d65be1c..ba93e2a6bdbb4 100644 --- a/net/sched/cls_u32.c +++ b/net/sched/cls_u32.c @@ -824,7 +824,6 @@ 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);