linux/net/sched/sch_fifo.c
Eric Dumazet 560ee196fe net_sched: fix NULL deref in fifo_set_limit()
syzbot reported another NULL deref in fifo_set_limit() [1]

I could repro the issue with :

unshare -n
tc qd add dev lo root handle 1:0 tbf limit 200000 burst 70000 rate 100Mbit
tc qd replace dev lo parent 1:0 pfifo_fast
tc qd change dev lo root handle 1:0 tbf limit 300000 burst 70000 rate 100Mbit

pfifo_fast does not have a change() operation.
Make fifo_set_limit() more robust about this.

[1]
BUG: kernel NULL pointer dereference, address: 0000000000000000
PGD 1cf99067 P4D 1cf99067 PUD 7ca49067 PMD 0
Oops: 0010 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 14443 Comm: syz-executor959 Not tainted 5.15.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:0x0
Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6.
RSP: 0018:ffffc9000e2f7310 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffffffff8d6ecc00 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffff888024c27910 RDI: ffff888071e34000
RBP: ffff888071e34000 R08: 0000000000000001 R09: ffffffff8fcfb947
R10: 0000000000000001 R11: 0000000000000000 R12: ffff888024c27910
R13: ffff888071e34018 R14: 0000000000000000 R15: ffff88801ef74800
FS:  00007f321d897700(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 00000000722c3000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 fifo_set_limit net/sched/sch_fifo.c:242 [inline]
 fifo_set_limit+0x198/0x210 net/sched/sch_fifo.c:227
 tbf_change+0x6ec/0x16d0 net/sched/sch_tbf.c:418
 qdisc_change net/sched/sch_api.c:1332 [inline]
 tc_modify_qdisc+0xd9a/0x1a60 net/sched/sch_api.c:1634
 rtnetlink_rcv_msg+0x413/0xb80 net/core/rtnetlink.c:5572
 netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2504
 netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
 netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1340
 netlink_sendmsg+0x86d/0xdb0 net/netlink/af_netlink.c:1929
 sock_sendmsg_nosec net/socket.c:704 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:724
 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2409
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2463
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2492
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Fixes: fb0305ce1b ("net-sched: consolidate default fifo qdisc setup")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Link: https://lore.kernel.org/r/20210930212239.3430364-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2021-10-01 14:59:10 -07:00

272 lines
6.0 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* net/sched/sch_fifo.c The simplest FIFO queue.
*
* Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
*/
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/skbuff.h>
#include <net/pkt_sched.h>
#include <net/pkt_cls.h>
/* 1 band FIFO pseudo-"scheduler" */
static int bfifo_enqueue(struct sk_buff *skb, struct Qdisc *sch,
struct sk_buff **to_free)
{
if (likely(sch->qstats.backlog + qdisc_pkt_len(skb) <= sch->limit))
return qdisc_enqueue_tail(skb, sch);
return qdisc_drop(skb, sch, to_free);
}
static int pfifo_enqueue(struct sk_buff *skb, struct Qdisc *sch,
struct sk_buff **to_free)
{
if (likely(sch->q.qlen < sch->limit))
return qdisc_enqueue_tail(skb, sch);
return qdisc_drop(skb, sch, to_free);
}
static int pfifo_tail_enqueue(struct sk_buff *skb, struct Qdisc *sch,
struct sk_buff **to_free)
{
unsigned int prev_backlog;
if (likely(sch->q.qlen < sch->limit))
return qdisc_enqueue_tail(skb, sch);
prev_backlog = sch->qstats.backlog;
/* queue full, remove one skb to fulfill the limit */
__qdisc_queue_drop_head(sch, &sch->q, to_free);
qdisc_qstats_drop(sch);
qdisc_enqueue_tail(skb, sch);
qdisc_tree_reduce_backlog(sch, 0, prev_backlog - sch->qstats.backlog);
return NET_XMIT_CN;
}
static void fifo_offload_init(struct Qdisc *sch)
{
struct net_device *dev = qdisc_dev(sch);
struct tc_fifo_qopt_offload qopt;
if (!tc_can_offload(dev) || !dev->netdev_ops->ndo_setup_tc)
return;
qopt.command = TC_FIFO_REPLACE;
qopt.handle = sch->handle;
qopt.parent = sch->parent;
dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_FIFO, &qopt);
}
static void fifo_offload_destroy(struct Qdisc *sch)
{
struct net_device *dev = qdisc_dev(sch);
struct tc_fifo_qopt_offload qopt;
if (!tc_can_offload(dev) || !dev->netdev_ops->ndo_setup_tc)
return;
qopt.command = TC_FIFO_DESTROY;
qopt.handle = sch->handle;
qopt.parent = sch->parent;
dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_FIFO, &qopt);
}
static int fifo_offload_dump(struct Qdisc *sch)
{
struct tc_fifo_qopt_offload qopt;
qopt.command = TC_FIFO_STATS;
qopt.handle = sch->handle;
qopt.parent = sch->parent;
qopt.stats.bstats = &sch->bstats;
qopt.stats.qstats = &sch->qstats;
return qdisc_offload_dump_helper(sch, TC_SETUP_QDISC_FIFO, &qopt);
}
static int __fifo_init(struct Qdisc *sch, struct nlattr *opt,
struct netlink_ext_ack *extack)
{
bool bypass;
bool is_bfifo = sch->ops == &bfifo_qdisc_ops;
if (opt == NULL) {
u32 limit = qdisc_dev(sch)->tx_queue_len;
if (is_bfifo)
limit *= psched_mtu(qdisc_dev(sch));
sch->limit = limit;
} else {
struct tc_fifo_qopt *ctl = nla_data(opt);
if (nla_len(opt) < sizeof(*ctl))
return -EINVAL;
sch->limit = ctl->limit;
}
if (is_bfifo)
bypass = sch->limit >= psched_mtu(qdisc_dev(sch));
else
bypass = sch->limit >= 1;
if (bypass)
sch->flags |= TCQ_F_CAN_BYPASS;
else
sch->flags &= ~TCQ_F_CAN_BYPASS;
return 0;
}
static int fifo_init(struct Qdisc *sch, struct nlattr *opt,
struct netlink_ext_ack *extack)
{
int err;
err = __fifo_init(sch, opt, extack);
if (err)
return err;
fifo_offload_init(sch);
return 0;
}
static int fifo_hd_init(struct Qdisc *sch, struct nlattr *opt,
struct netlink_ext_ack *extack)
{
return __fifo_init(sch, opt, extack);
}
static void fifo_destroy(struct Qdisc *sch)
{
fifo_offload_destroy(sch);
}
static int __fifo_dump(struct Qdisc *sch, struct sk_buff *skb)
{
struct tc_fifo_qopt opt = { .limit = sch->limit };
if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
goto nla_put_failure;
return skb->len;
nla_put_failure:
return -1;
}
static int fifo_dump(struct Qdisc *sch, struct sk_buff *skb)
{
int err;
err = fifo_offload_dump(sch);
if (err)
return err;
return __fifo_dump(sch, skb);
}
static int fifo_hd_dump(struct Qdisc *sch, struct sk_buff *skb)
{
return __fifo_dump(sch, skb);
}
struct Qdisc_ops pfifo_qdisc_ops __read_mostly = {
.id = "pfifo",
.priv_size = 0,
.enqueue = pfifo_enqueue,
.dequeue = qdisc_dequeue_head,
.peek = qdisc_peek_head,
.init = fifo_init,
.destroy = fifo_destroy,
.reset = qdisc_reset_queue,
.change = fifo_init,
.dump = fifo_dump,
.owner = THIS_MODULE,
};
EXPORT_SYMBOL(pfifo_qdisc_ops);
struct Qdisc_ops bfifo_qdisc_ops __read_mostly = {
.id = "bfifo",
.priv_size = 0,
.enqueue = bfifo_enqueue,
.dequeue = qdisc_dequeue_head,
.peek = qdisc_peek_head,
.init = fifo_init,
.destroy = fifo_destroy,
.reset = qdisc_reset_queue,
.change = fifo_init,
.dump = fifo_dump,
.owner = THIS_MODULE,
};
EXPORT_SYMBOL(bfifo_qdisc_ops);
struct Qdisc_ops pfifo_head_drop_qdisc_ops __read_mostly = {
.id = "pfifo_head_drop",
.priv_size = 0,
.enqueue = pfifo_tail_enqueue,
.dequeue = qdisc_dequeue_head,
.peek = qdisc_peek_head,
.init = fifo_hd_init,
.reset = qdisc_reset_queue,
.change = fifo_hd_init,
.dump = fifo_hd_dump,
.owner = THIS_MODULE,
};
/* Pass size change message down to embedded FIFO */
int fifo_set_limit(struct Qdisc *q, unsigned int limit)
{
struct nlattr *nla;
int ret = -ENOMEM;
/* Hack to avoid sending change message to non-FIFO */
if (strncmp(q->ops->id + 1, "fifo", 4) != 0)
return 0;
if (!q->ops->change)
return 0;
nla = kmalloc(nla_attr_size(sizeof(struct tc_fifo_qopt)), GFP_KERNEL);
if (nla) {
nla->nla_type = RTM_NEWQDISC;
nla->nla_len = nla_attr_size(sizeof(struct tc_fifo_qopt));
((struct tc_fifo_qopt *)nla_data(nla))->limit = limit;
ret = q->ops->change(q, nla, NULL);
kfree(nla);
}
return ret;
}
EXPORT_SYMBOL(fifo_set_limit);
struct Qdisc *fifo_create_dflt(struct Qdisc *sch, struct Qdisc_ops *ops,
unsigned int limit,
struct netlink_ext_ack *extack)
{
struct Qdisc *q;
int err = -ENOMEM;
q = qdisc_create_dflt(sch->dev_queue, ops, TC_H_MAKE(sch->handle, 1),
extack);
if (q) {
err = fifo_set_limit(q, limit);
if (err < 0) {
qdisc_put(q);
q = NULL;
}
}
return q ? : ERR_PTR(err);
}
EXPORT_SYMBOL(fifo_create_dflt);