net/sched: fix infinite loop in sch_fq_pie

this command hangs forever: # tc qdisc add dev eth0 root fq_pie flows 65536 watchdog: BUG: soft lockup - CPU#1 stuck for 23s! [tc:1028] [...] CPU: 1 PID: 1028 Comm: tc Not tainted 5.7.0-rc6+ torvalds#167 RIP: 0010:fq_pie_init+0x60e/0x8b7 [sch_fq_pie] Code: 4c 89 65 50 48 89 f8 48 c1 e8 03 42 80 3c 30 00 0f 85 2a 02 00 00 48 8d 7d 10 4c 89 65 58 48 89 f8 48 c1 e8 03 42 80 3c 30 00 <0f> 85 a7 01 00 00 48 8d 7d 18 48 c7 45 10 46 c3 23 00 48 89 f8 48 RSP: 0018:ffff888138d67468 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 RAX: 1ffff9200018d2b2 RBX: ffff888139c1c400 RCX: ffffffffffffffff RDX: 000000000000c5e8 RSI: ffffc900000e5000 RDI: ffffc90000c69590 RBP: ffffc90000c69580 R08: fffffbfff79a9699 R09: fffffbfff79a9699 R10: 0000000000000700 R11: fffffbfff79a9698 R12: ffffc90000c695d0 R13: 0000000000000000 R14: dffffc0000000000 R15: 000000002347c5e8 FS: 00007f01e1850e40(0000) GS:ffff88814c880000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000000067c340 CR3: 000000013864c000 CR4: 0000000000340ee0 Call Trace: qdisc_create+0x3fd/0xeb0 tc_modify_qdisc+0x3be/0x14a0 rtnetlink_rcv_msg+0x5f3/0x920 netlink_rcv_skb+0x121/0x350 netlink_unicast+0x439/0x630 netlink_sendmsg+0x714/0xbf0 sock_sendmsg+0xe2/0x110 ____sys_sendmsg+0x5b4/0x890 ___sys_sendmsg+0xe9/0x160 __sys_sendmsg+0xd3/0x170 do_syscall_64+0x9a/0x370 entry_SYSCALL_64_after_hwframe+0x44/0xa9 we can't accept 65536 as a valid number for 'nflows', because the loop on 'idx' in fq_pie_init() will never end. The extack message is correct, but it doesn't say that 0 is not a valid number for 'flows': while at it, fix this also. Add a tdc selftest to check correct validation of 'flows'. CC: Ivan Vecera <[email protected]> Fixes: ec97ecf ("net: sched: add Flow Queue PIE packet scheduler") Signed-off-by: Davide Caratti <[email protected]> Reviewed-by: Ivan Vecera <[email protected]> Signed-off-by: David S. Miller <[email protected]>
vpsfreecz · May 27, 2020 · bb2f930 · bb2f930
1 parent a4976a3
commit bb2f930
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Showing 2 changed files with 23 additions and 2 deletions.
diff --git a/net/sched/sch_fq_pie.c b/net/sched/sch_fq_pie.c
@@ -297,9 +297,9 @@ static int fq_pie_change(struct Qdisc *sch, struct nlattr *opt,
 			goto flow_error;
 		}
 		q->flows_cnt = nla_get_u32(tb[TCA_FQ_PIE_FLOWS]);
-		if (!q->flows_cnt || q->flows_cnt > 65536) {
+		if (!q->flows_cnt || q->flows_cnt >= 65536) {
 			NL_SET_ERR_MSG_MOD(extack,
-					   "Number of flows must be < 65536");
+					   "Number of flows must range in [1..65535]");
 			goto flow_error;
 		}
 	}

diff --git a/tools/testing/selftests/tc-testing/tc-tests/qdiscs/fq_pie.json b/tools/testing/selftests/tc-testing/tc-tests/qdiscs/fq_pie.json
@@ -0,0 +1,21 @@
+[
+    {
+        "id": "83be",
+        "name": "Create FQ-PIE with invalid number of flows",
+        "category": [
+            "qdisc",
+            "fq_pie"
+        ],
+        "setup": [
+            "$IP link add dev $DUMMY type dummy || /bin/true"
+        ],
+        "cmdUnderTest": "$TC qdisc add dev $DUMMY root fq_pie flows 65536",
+        "expExitCode": "2",
+        "verifyCmd": "$TC qdisc show dev $DUMMY",
+        "matchPattern": "qdisc",
+        "matchCount": "0",
+        "teardown": [
+            "$IP link del dev $DUMMY"
+        ]
+    }
+]