Commit e18f3486 authored by Victor Nogueira's avatar Victor Nogueira Committed by Jakub Kicinski
Browse files

selftests/tc-testing: Create test cases for adding qdiscs to invalid qdisc parents 

As described in a previous commit [1], Lion's patch [2] revealed an ancient
bug in the qdisc API. Whenever a user tries to add a qdisc to an
invalid parent (not a class, root, or ingress qdisc), the qdisc API will
detect this after qdisc_create is called. Some qdiscs (like fq_codel, pie,
and sfq) call functions (on their init callback) which assume the parent is
valid, so qdisc_create itself may have caused a NULL pointer dereference in
such cases.

This commit creates 3 TDC tests that attempt to add fq_codel, pie and sfq
qdiscs to invalid parents

- Attempts to add an fq_codel qdisc to an hhf qdisc parent
- Attempts to add a pie qdisc to a drr qdisc parent
- Attempts to add an sfq qdisc to an inexistent hfsc classid (which would
  belong to a valid hfsc qdisc)

[1] https://lore.kernel.org/all/20250707210801.372995-1-victor@mojatatu.com/
[2] https://lore.kernel.org/netdev/d912cbd7-193b-4269-9857-525bee8bbb6a@gmail.com/



Signed-off-by: default avatarVictor Nogueira <victor@mojatatu.com>
Link: https://patch.msgid.link/20250712145035.705156-1-victor@mojatatu.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 60ada4fe

tools/testing/selftests/tc-testing/tc-tests/infra/qdiscs.json

+66 −0
Original line number Diff line number Diff line
@@ -672,5 +672,71 @@ 
        "teardown": [

            "$TC qdisc del dev $DUMMY root handle 1: drr"

        ]

    },

    {

        "id": "be28",

        "name": "Try to add fq_codel qdisc as a child of an hhf qdisc",

        "category": [

            "qdisc",

            "fq_codel",

            "hhf"

        ],

        "plugins": {

            "requires": "nsPlugin"

        },

        "setup": [

            "$TC qdisc add dev $DUMMY root handle a: hhf"

        ],

        "cmdUnderTest": "$TC qdisc add dev $DUMMY parent a: handle b: fq_codel",

        "expExitCode": "2",

        "verifyCmd": "$TC -j qdisc ls dev $DUMMY handle b:",

        "matchJSON": [],

        "teardown": [

            "$TC qdisc del dev $DUMMY root"

        ]

    },

    {

        "id": "fcb5",

        "name": "Try to add pie qdisc as a child of a drr qdisc",

        "category": [

            "qdisc",

            "pie",

            "drr"

        ],

        "plugins": {

            "requires": "nsPlugin"

        },

        "setup": [

            "$TC qdisc add dev $DUMMY root handle a: drr"

        ],

        "cmdUnderTest": "$TC qdisc add dev $DUMMY parent a: handle b: pie",

        "expExitCode": "2",

        "verifyCmd": "$TC -j qdisc ls dev $DUMMY handle b:",

        "matchJSON": [],

        "teardown": [

            "$TC qdisc del dev $DUMMY root"

        ]

    },

    {

        "id": "7801",

        "name": "Try to add fq qdisc as a child of an inexistent hfsc class",

        "category": [

            "qdisc",

            "sfq",

            "hfsc"

        ],

        "plugins": {

            "requires": "nsPlugin"

        },

        "setup": [

            "$TC qdisc add dev $DUMMY root handle a: hfsc"

        ],

        "cmdUnderTest": "$TC qdisc add dev $DUMMY parent a:fff2 sfq limit 4",

        "expExitCode": "2",

        "verifyCmd": "$TC -j qdisc ls dev $DUMMY handle b:",

        "matchJSON": [],

        "teardown": [

            "$TC qdisc del dev $DUMMY root"

        ]

    }

]