Re: [PATCH net v1] net/sched: cls_api: complement tcf_tfilter_dump_policy
From: Jamal Hadi Salim <jhs@mojatatu.com>
Date: 2023-12-25 23:04:26
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Hi, On Sun, Dec 24, 2023 at 11:54 AM Lin Ma [off-list ref] wrote:
In function `tc_dump_tfilter`, the attributes array is parsed via
tcf_tfilter_dump_policy which only describes TCA_DUMP_FLAGS. However,
the NLA TCA_CHAIN is also accessed with `nla_get_u32`. According to the
commit 5e2424708da7 ("xfrm: add forgotten nla_policy for
XFRMA_MTIMER_THRESH"), such a missing piece could lead to a potential
heap data leak.Can you clarify what "heap data leak" you are referring to? As much as i can see any reference to NLA_TCA_CHAIN is checked for presence before being put to use. So far that reason I dont see how this patch qualifies as "net". It looks like an enhancement to me which should target net-next, unless i am missing something obvious. cheers, jamal
quoted hunk ↗ jump to hunk
The access to TCA_CHAIN is introduced in commit 5bc1701881e3 ("net: sched: introduce multichain support for filters") and no nla_policy is provided for parsing at that point. Later on, tcf_tfilter_dump_policy is introduced in commit f8ab1807a9c9 ("net: sched: introduce terse dump flag") while still ignoring the fact that TCA_CHAIN needs a check. This patch does that by complementing the policy. Note that other functions that access TCA_CHAIN, like tc_new_tfilter, are not vulnerable as they choose rtm_tca_policy as the parsing policy which describes the TCA_CHAIN already. Fixes: 5bc1701881e3 ("net: sched: introduce multichain support for filters") Signed-off-by: Lin Ma <redacted> --- net/sched/cls_api.c | 1 + 1 file changed, 1 insertion(+)diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c index 1976bd163986..2b5b8eca2ee3 100644 --- a/net/sched/cls_api.c +++ b/net/sched/cls_api.c@@ -2732,6 +2732,7 @@ static bool tcf_chain_dump(struct tcf_chain *chain, struct Qdisc *q, u32 parent, } static const struct nla_policy tcf_tfilter_dump_policy[TCA_MAX + 1] = { + [TCA_CHAIN] = { .type = NLA_U32 }, [TCA_DUMP_FLAGS] = NLA_POLICY_BITFIELD32(TCA_DUMP_FLAGS_TERSE), }; --2.17.1