From: Vladimir Oltean vladimir.oltean@nxp.com

[ Upstream commit fb66df20a7201e60f2b13d7f95d031b31a8831d3 ]

It is possible for syzbot to side-step the restriction imposed by the blamed commit in the Fixes: tag, because the taprio UAPI permits a cycle-time different from (and potentially shorter than) the sum of entry intervals.

We need one more restriction, which is that the cycle time itself must be larger than N * ETH_ZLEN bit times, where N is the number of schedule entries. This restriction needs to apply regardless of whether the cycle time came from the user or was the implicit, auto-calculated value, so we move the existing "cycle == 0" check outside the "if "(!new->cycle_time)" branch. This way covers both conditions and scenarios.

Add a selftest which illustrates the issue triggered by syzbot.

Fixes: b5b73b26b3ca ("taprio: Fix allowing too small intervals") Reported-by: syzbot+a7d2b1d5d1af83035567@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/0000000000007d66bc06196e7c66@google.com/ Signed-off-by: Vladimir Oltean vladimir.oltean@nxp.com Link: https://lore.kernel.org/r/20240527153955.553333-2-vladimir.oltean@nxp.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Xiangyu Chen xiangyu.chen@windriver.com --- net/sched/sch_taprio.c | 10 ++++----- .../tc-testing/tc-tests/qdiscs/taprio.json | 22 +++++++++++++++++++ 2 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c index 1d5cdc987abd..62219f23f76a 100644 --- a/net/sched/sch_taprio.c +++ b/net/sched/sch_taprio.c @@ -915,11 +915,6 @@ static int parse_taprio_schedule(struct taprio_sched *q, struct nlattr **tb, list_for_each_entry(entry, &new->entries, list) cycle = ktime_add_ns(cycle, entry->interval);

- if (!cycle) { - NL_SET_ERR_MSG(extack, "'cycle_time' can never be 0"); - return -EINVAL; - } - if (cycle < 0 || cycle > INT_MAX) { NL_SET_ERR_MSG(extack, "'cycle_time' is too big"); return -EINVAL; @@ -928,6 +923,11 @@ static int parse_taprio_schedule(struct taprio_sched *q, struct nlattr **tb, new->cycle_time = cycle; }

+ if (new->cycle_time < new->num_entries * length_to_duration(q, ETH_ZLEN)) { + NL_SET_ERR_MSG(extack, "'cycle_time' is too small"); + return -EINVAL; + } + return 0; }

diff --git a/tools/testing/selftests/tc-testing/tc-tests/qdiscs/taprio.json b/tools/testing/selftests/tc-testing/tc-tests/qdiscs/taprio.json index 08d4861c2e78..d04fed83332c 100644 --- a/tools/testing/selftests/tc-testing/tc-tests/qdiscs/taprio.json +++ b/tools/testing/selftests/tc-testing/tc-tests/qdiscs/taprio.json @@ -132,6 +132,28 @@ "echo "1" > /sys/bus/netdevsim/del_device" ] }, + { + "id": "831f", + "name": "Add taprio Qdisc with too short cycle-time", + "category": [ + "qdisc", + "taprio" + ], + "plugins": { + "requires": "nsPlugin" + }, + "setup": [ + "echo "1 1 8" > /sys/bus/netdevsim/new_device" + ], + "cmdUnderTest": "$TC qdisc add dev $ETH root handle 1: taprio num_tc 2 queues 1@0 1@1 sched-entry S 01 200000 sched-entry S 02 200000 cycle-time 100 clockid CLOCK_TAI", + "expExitCode": "2", + "verifyCmd": "$TC qdisc show dev $ETH", + "matchPattern": "qdisc taprio 1: root refcnt", + "matchCount": "0", + "teardown": [ + "echo "1" > /sys/bus/netdevsim/del_device" + ] + }, { "id": "3e1e", "name": "Add taprio Qdisc with an invalid cycle-time",