From: Davide Caratti dcaratti@redhat.com
[ Upstream commit 7041101ff6c3073fd8f2e99920f535b111c929cb ]
if sch_fq is configured with "initial quantum" having values greater than INT_MAX, the first assignment of "credit" does signed integer overflow to a very negative value. In this situation, the syzkaller script provided by Cristoph triggers the CPU soft-lockup warning even with few sockets. It's not an infinite loop, but "credit" wasn't probably meant to be minus 2Gb for each new flow. Capping "initial quantum" to INT_MAX proved to fix the issue.
v2: validation of "initial quantum" is done in fq_policy, instead of open coding in fq_change() _ suggested by Jakub Kicinski
Reported-by: Christoph Paasch cpaasch@apple.com Link: https://github.com/multipath-tcp/mptcp_net-next/issues/377 Fixes: afe4fd062416 ("pkt_sched: fq: Fair Queue packet scheduler") Reviewed-by: Eric Dumazet edumazet@google.com Signed-off-by: Davide Caratti dcaratti@redhat.com Link: https://lore.kernel.org/r/7b3a3c7e36d03068707a021760a194a8eb5ad41a.168200230... Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/sched/sch_fq.c | 6 ++++- .../tc-testing/tc-tests/qdiscs/fq.json | 22 +++++++++++++++++++ 2 files changed, 27 insertions(+), 1 deletion(-)
diff --git a/net/sched/sch_fq.c b/net/sched/sch_fq.c index 48d14fb90ba02..f59a2cb2c803d 100644 --- a/net/sched/sch_fq.c +++ b/net/sched/sch_fq.c @@ -779,13 +779,17 @@ static int fq_resize(struct Qdisc *sch, u32 log) return 0; }
+static struct netlink_range_validation iq_range = { + .max = INT_MAX, +}; + static const struct nla_policy fq_policy[TCA_FQ_MAX + 1] = { [TCA_FQ_UNSPEC] = { .strict_start_type = TCA_FQ_TIMER_SLACK },
[TCA_FQ_PLIMIT] = { .type = NLA_U32 }, [TCA_FQ_FLOW_PLIMIT] = { .type = NLA_U32 }, [TCA_FQ_QUANTUM] = { .type = NLA_U32 }, - [TCA_FQ_INITIAL_QUANTUM] = { .type = NLA_U32 }, + [TCA_FQ_INITIAL_QUANTUM] = NLA_POLICY_FULL_RANGE(NLA_U32, &iq_range), [TCA_FQ_RATE_ENABLE] = { .type = NLA_U32 }, [TCA_FQ_FLOW_DEFAULT_RATE] = { .type = NLA_U32 }, [TCA_FQ_FLOW_MAX_RATE] = { .type = NLA_U32 }, diff --git a/tools/testing/selftests/tc-testing/tc-tests/qdiscs/fq.json b/tools/testing/selftests/tc-testing/tc-tests/qdiscs/fq.json index 8acb904d14193..3593fb8f79ad3 100644 --- a/tools/testing/selftests/tc-testing/tc-tests/qdiscs/fq.json +++ b/tools/testing/selftests/tc-testing/tc-tests/qdiscs/fq.json @@ -114,6 +114,28 @@ "$IP link del dev $DUMMY type dummy" ] }, + { + "id": "10f7", + "name": "Create FQ with invalid initial_quantum setting", + "category": [ + "qdisc", + "fq" + ], + "plugins": { + "requires": "nsPlugin" + }, + "setup": [ + "$IP link add dev $DUMMY type dummy || /bin/true" + ], + "cmdUnderTest": "$TC qdisc add dev $DUMMY handle 1: root fq initial_quantum 0x80000000", + "expExitCode": "2", + "verifyCmd": "$TC qdisc show dev $DUMMY", + "matchPattern": "qdisc fq 1: root.*initial_quantum 2048Mb", + "matchCount": "0", + "teardown": [ + "$IP link del dev $DUMMY type dummy" + ] + }, { "id": "9398", "name": "Create FQ with maxrate setting",