UBSAN: array-index-out-of-bounds in qfq_update

UBSAN: array-index-out-of-bounds in qfq_update_agg
Status: upstream: reported on 2021/01/06 08:50
Reported-by: syzbot+7c315a573dd9374a3220@syzkaller.appspotmail.com
First crash: 108d, last: 94d

Sample crash report:

netlink: 24 bytes leftover after parsing attributes in process `syz-executor.5'.
================================================================================
UBSAN: array-index-out-of-bounds in net/sched/sch_qfq.c:300:24
index 29 is out of range for type 'qfq_group [25]'
CPU: 0 PID: 15762 Comm: syz-executor.5 Not tainted 5.11.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x107/0x163 lib/dump_stack.c:120
 ubsan_epilogue+0xb/0x5a lib/ubsan.c:148
 __ubsan_handle_out_of_bounds.cold+0x62/0x6c lib/ubsan.c:356
 qfq_update_agg+0x6e9/0x700 net/sched/sch_qfq.c:300
 qfq_add_to_agg+0x75/0x500 net/sched/sch_qfq.c:317
 qfq_change_class+0x5cd/0x1780 net/sched/sch_qfq.c:510
 tc_ctl_tclass+0x525/0xe50 net/sched/sch_api.c:2111
 rtnetlink_rcv_msg+0x44e/0xad0 net/core/rtnetlink.c:5553
 netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2494
 netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline]
 netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1330
 netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1919
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:672
 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2345
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2399
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2432
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45e219
Code: 0d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 db b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fb23be88c68 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045e219
RDX: 0000000000000000 RSI: 0000000020000280 RDI: 0000000000000005
RBP: 000000000119c068 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000119c034
R13: 00007ffd1232244f R14: 00007fb23be899c0 R15: 000000000119c034
================================================================================

Crashes (2):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Title
ci-upstream-net-kasan-gce	2021/01/16 21:19	net-next	9ab7e76a	65a7a854	.config	log	report			info
ci-upstream-net-kasan-gce	2021/01/02 08:40	net-next	3db1a3fa	79264ae3	.config	log	report			info