From: Davide Caratti <dcaratti@xxxxxxxxxx>
[ 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@xxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: Davide Caratti <dcaratti@xxxxxxxxxx>
Link: https://lore.kernel.org/r/7b3a3c7e36d03068707a021760a194a8eb5ad41a.1682002300.git.dcaratti@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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",
--
2.39.2
