From: Eric Dumazet <edumazet@xxxxxxxxxx>
commit 7d18a07897d07495ee140dd319b0e9265c0f68ba upstream.
tx_queue_len can be set to ~0U, we need to be more
careful about overflows.
__fls(0) is undefined, as this report shows:
UBSAN: shift-out-of-bounds in net/sched/sch_qfq.c:1430:24
shift exponent 51770272 is too large for 32-bit type 'int'
CPU: 0 PID: 25574 Comm: syz-executor.0 Not tainted 5.16.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x201/0x2d8 lib/dump_stack.c:106
ubsan_epilogue lib/ubsan.c:151 [inline]
__ubsan_handle_shift_out_of_bounds+0x494/0x530 lib/ubsan.c:330
qfq_init_qdisc+0x43f/0x450 net/sched/sch_qfq.c:1430
qdisc_create+0x895/0x1430 net/sched/sch_api.c:1253
tc_modify_qdisc+0x9d9/0x1e20 net/sched/sch_api.c:1660
rtnetlink_rcv_msg+0x934/0xe60 net/core/rtnetlink.c:5571
netlink_rcv_skb+0x200/0x470 net/netlink/af_netlink.c:2496
netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
netlink_unicast+0x814/0x9f0 net/netlink/af_netlink.c:1345
netlink_sendmsg+0xaea/0xe60 net/netlink/af_netlink.c:1921
sock_sendmsg_nosec net/socket.c:704 [inline]
sock_sendmsg net/socket.c:724 [inline]
____sys_sendmsg+0x5b9/0x910 net/socket.c:2409
___sys_sendmsg net/socket.c:2463 [inline]
__sys_sendmsg+0x280/0x370 net/socket.c:2492
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
Fixes: 462dbc9101ac ("pkt_sched: QFQ Plus: fair-queueing service at DRR cost")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Reported-by: syzbot <syzkaller@xxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/sched/sch_qfq.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
--- a/net/sched/sch_qfq.c
+++ b/net/sched/sch_qfq.c
@@ -1422,10 +1422,8 @@ static int qfq_init_qdisc(struct Qdisc *
if (err < 0)
return err;
- if (qdisc_dev(sch)->tx_queue_len + 1 > QFQ_MAX_AGG_CLASSES)
- max_classes = QFQ_MAX_AGG_CLASSES;
- else
- max_classes = qdisc_dev(sch)->tx_queue_len + 1;
+ max_classes = min_t(u64, (u64)qdisc_dev(sch)->tx_queue_len + 1,
+ QFQ_MAX_AGG_CLASSES);
/* max_cl_shift = floor(log_2(max_classes)) */
max_cl_shift = __fls(max_classes);
q->max_agg_classes = 1<<max_cl_shift;
