Re: [PATCH net 3/3] selftests/tc-testing: Verify bpf redirect on RED block with preceding clsact (egress) classifier

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Hardcoded BPF object path 'action-ebpf' instead of using '$EBPFDIR/action-ebpf'.
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commit f4ff308069725bd7a3b6c6f843ecb0fda5b73239
Author: Victor Nogueira <victor@mojatatu.com>

selftests/tc-testing: Verify bpf redirect on RED block with preceding clsact (egress) classifier

This commit adds a test case to reproduce a NULL pointer dereference when a
bpf filter attached to a RED block (which uses shared blocks) returns
TC_ACT_REDIRECT while a preceding clsact egress classifier is present. The
issue stems from a stack-allocated bpf_net_context being torn down before
tcf_qevent_handle() calls skb_do_redirect().

> diff --git a/tools/testing/selftests/tc-testing/tc-tests/infra/qdiscs.json b/tools/testing/selftests/tc-testing/tc-tests/infra/qdiscs.json
> index a1f97a4b606e8..762f86ceab1cd 100644
> --- a/tools/testing/selftests/tc-testing/tc-tests/infra/qdiscs.json
> +++ b/tools/testing/selftests/tc-testing/tc-tests/infra/qdiscs.json
[ ... ]
> @@ -1540,5 +1540,37 @@
[ ... ]
> +    {
> +        "id": "fb8d",
> +        "name": "Verify bpf redirect on RED block with preceding clsact (egress) classifier",
> +        "category": [
> +            "qdisc",
> +            "red",
> +            "qevent",
> +            "clsact"
> +        ],
> +        "plugins": {
> +            "requires": "nsPlugin"
> +        },
> +        "setup": [
> +            "$IP addr add 10.10.10.1/24 dev $DUMMY",
> +            "$IP neigh add 10.10.10.2 lladdr 02:00:00:00:00:01 dev $DUMMY nud permanent",
> +            "$TC qdisc add dev $DUMMY handle 1: root tbf rate 1Mbit burst 10K limit 1M",
> +            "$TC qdisc add dev $DUMMY parent 1:1 handle 11: red limit 1M avpkt 1400 probability 1 burst 38 harddrop min 30000 max 30001 qevent early_drop block 10",
> +            "$TC qdisc add dev $DUMMY clsact",
> +            "$TC filter add dev $DUMMY egress protocol ip prio 1 matchall action gact pass",
> +            "$TC filter add block 10 protocol ip prio 1 matchall action bpf obj action-ebpf sec action-redirect"

[Severity: Medium]
In the setup block for "Verify bpf redirect on RED block with preceding clsact
(egress) classifier", will this test fail with a file-not-found error when
the tdc.py runner is executed in an out-of-tree build environment or with a
customized $EBPFDIR?

Should this path be updated to use $EBPFDIR/action-ebpf instead of the
hardcoded action-ebpf so it aligns with other tests in the suite and finds
the BPF object correctly?

> +        ],
> +        "cmdUnderTest": "bash -c 'data=$(head -c 1400 /dev/zero | tr \"\\0\" \"x\"); exec 3>/dev/udp/10.10.10.2/12345; for i in $(seq 1 8000); do printf \"%s\" \"$data\" >&3; done; exit 0'",
[ ... ]

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Sashiko AI review · https://sashiko.dev/#/patchset/20260626165156.169012-1-jhs@mojatatu.com?part=3