[PATCH 3.2 073/147] sch_cbq: fix null pointer dereferences on init failure
From: Ben Hutchings
Date: Mon Nov 06 2017 - 18:31:08 EST
3.2.95-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Nikolay Aleksandrov <nikolay@xxxxxxxxxxxxxxxxxxx>
commit 3501d059921246ff617b43e86250a719c140bd97 upstream.
CBQ can fail on ->init by wrong nl attributes or simply for missing any,
f.e. if it's set as a default qdisc then TCA_OPTIONS (opt) will be NULL
when it is activated. The first thing init does is parse opt but it will
dereference a null pointer if used as a default qdisc, also since init
failure at default qdisc invokes ->reset() which cancels all timers then
we'll also dereference two more null pointers (timer->base) as they were
never initialized.
To reproduce:
$ sysctl net.core.default_qdisc=cbq
$ ip l set ethX up
Crash log of the first null ptr deref:
[44727.907454] BUG: unable to handle kernel NULL pointer dereference at (null)
[44727.907600] IP: cbq_init+0x27/0x205
[44727.907676] PGD 59ff4067
[44727.907677] P4D 59ff4067
[44727.907742] PUD 59c70067
[44727.907807] PMD 0
[44727.907873]
[44727.907982] Oops: 0000 [#1] SMP
[44727.908054] Modules linked in:
[44727.908126] CPU: 1 PID: 21312 Comm: ip Not tainted 4.13.0-rc6+ #60
[44727.908235] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140531_083030-gandalf 04/01/2014
[44727.908477] task: ffff88005ad42700 task.stack: ffff880037214000
[44727.908672] RIP: 0010:cbq_init+0x27/0x205
[44727.908838] RSP: 0018:ffff8800372175f0 EFLAGS: 00010286
[44727.909018] RAX: ffffffff816c3852 RBX: ffff880058c53800 RCX: 0000000000000000
[44727.909222] RDX: 0000000000000004 RSI: 0000000000000000 RDI: ffff8800372175f8
[44727.909427] RBP: ffff880037217650 R08: ffffffff81b0f380 R09: 0000000000000000
[44727.909631] R10: ffff880037217660 R11: 0000000000000020 R12: ffffffff822a44c0
[44727.909835] R13: ffff880058b92000 R14: 00000000ffffffff R15: 0000000000000001
[44727.910040] FS: 00007ff8bc583740(0000) GS:ffff88005d880000(0000) knlGS:0000000000000000
[44727.910339] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[44727.910525] CR2: 0000000000000000 CR3: 00000000371e5000 CR4: 00000000000406e0
[44727.910731] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[44727.910936] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[44727.911141] Call Trace:
[44727.911291] ? lockdep_init_map+0xb6/0x1ba
[44727.911461] ? qdisc_alloc+0x14e/0x187
[44727.911626] qdisc_create_dflt+0x7a/0x94
[44727.911794] ? dev_activate+0x129/0x129
[44727.911959] attach_one_default_qdisc+0x36/0x63
[44727.912132] netdev_for_each_tx_queue+0x3d/0x48
[44727.912305] dev_activate+0x4b/0x129
[44727.912468] __dev_open+0xe7/0x104
[44727.912631] __dev_change_flags+0xc6/0x15c
[44727.912799] dev_change_flags+0x25/0x59
[44727.912966] do_setlink+0x30c/0xb3f
[44727.913129] ? check_chain_key+0xb0/0xfd
[44727.913294] ? check_chain_key+0xb0/0xfd
[44727.913463] rtnl_newlink+0x3a4/0x729
[44727.913626] ? rtnl_newlink+0x117/0x729
[44727.913801] ? ns_capable_common+0xd/0xb1
[44727.913968] ? ns_capable+0x13/0x15
[44727.914131] rtnetlink_rcv_msg+0x188/0x197
[44727.914300] ? rcu_read_unlock+0x3e/0x5f
[44727.914465] ? rtnl_newlink+0x729/0x729
[44727.914630] netlink_rcv_skb+0x6c/0xce
[44727.914796] rtnetlink_rcv+0x23/0x2a
[44727.914956] netlink_unicast+0x103/0x181
[44727.915122] netlink_sendmsg+0x326/0x337
[44727.915291] sock_sendmsg_nosec+0x14/0x3f
[44727.915459] sock_sendmsg+0x29/0x2e
[44727.915619] ___sys_sendmsg+0x209/0x28b
[44727.915784] ? do_raw_spin_unlock+0xcd/0xf8
[44727.915954] ? _raw_spin_unlock+0x27/0x31
[44727.916121] ? __handle_mm_fault+0x651/0xdb1
[44727.916290] ? check_chain_key+0xb0/0xfd
[44727.916461] __sys_sendmsg+0x45/0x63
[44727.916626] ? __sys_sendmsg+0x45/0x63
[44727.916792] SyS_sendmsg+0x19/0x1b
[44727.916950] entry_SYSCALL_64_fastpath+0x23/0xc2
[44727.917125] RIP: 0033:0x7ff8bbc96690
[44727.917286] RSP: 002b:00007ffc360991e8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
[44727.917579] RAX: ffffffffffffffda RBX: ffffffff810d278c RCX: 00007ff8bbc96690
[44727.917783] RDX: 0000000000000000 RSI: 00007ffc36099230 RDI: 0000000000000003
[44727.917987] RBP: ffff880037217f98 R08: 0000000000000001 R09: 0000000000000003
[44727.918190] R10: 00007ffc36098fb0 R11: 0000000000000246 R12: 0000000000000006
[44727.918393] R13: 000000000066f1a0 R14: 00007ffc360a12e0 R15: 0000000000000000
[44727.918597] ? trace_hardirqs_off_caller+0xa7/0xcf
[44727.918774] Code: 41 5f 5d c3 66 66 66 66 90 55 48 8d 56 04 45 31 c9
49 c7 c0 80 f3 b0 81 48 89 e5 41 55 41 54 53 48 89 fb 48 8d 7d a8 48 83
ec 48 <0f> b7 0e be 07 00 00 00 83 e9 04 e8 e6 f7 d8 ff 85 c0 0f 88 bb
[44727.919332] RIP: cbq_init+0x27/0x205 RSP: ffff8800372175f0
[44727.919516] CR2: 0000000000000000
Fixes: 0fbbeb1ba43b ("[PKT_SCHED]: Fix missing qdisc_destroy() in qdisc_create_dflt()")
Signed-off-by: Nikolay Aleksandrov <nikolay@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
[bwh: Backported to 3.2:
- Keep using HRTIMER_MODE_ABS
- Adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
net/sched/sch_cbq.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
--- a/net/sched/sch_cbq.c
+++ b/net/sched/sch_cbq.c
@@ -1367,6 +1367,13 @@ static int cbq_init(struct Qdisc *sch, s
struct tc_ratespec *r;
int err;
+ qdisc_watchdog_init(&q->watchdog, sch);
+ hrtimer_init(&q->delay_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
+ q->delay_timer.function = cbq_undelay;
+
+ if (!opt)
+ return -EINVAL;
+
err = nla_parse_nested(tb, TCA_CBQ_MAX, opt, cbq_policy);
if (err < 0)
return err;
@@ -1405,9 +1412,6 @@ static int cbq_init(struct Qdisc *sch, s
q->link.avpkt = q->link.allot/2;
q->link.minidle = -0x7FFFFFFF;
- qdisc_watchdog_init(&q->watchdog, sch);
- hrtimer_init(&q->delay_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
- q->delay_timer.function = cbq_undelay;
q->toplevel = TC_CBQ_MAXLEVEL;
q->now = psched_get_time();
q->now_rt = q->now;