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Message-Id: <1504033335-19098-1-git-send-email-nikolay@cumulusnetworks.com>
Date: Tue, 29 Aug 2017 22:02:15 +0300
From: Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
To: netdev@...r.kernel.org
Cc: edumazet@...gle.com, jhs@...atatu.com, xiyou.wangcong@...il.com,
jiri@...nulli.us, roopa@...ulusnetworks.com,
Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
Subject: [PATCH net] sch_hhf: fix null pointer dereference on init failure
If sch_hhf fails in its ->init() function (either due to wrong
user-space arguments as below or memory alloc failure of hh_flows) it
will do a null pointer deref of q->hh_flows in its ->destroy() function.
To reproduce the crash:
$ tc qdisc add dev eth0 root hhf quantum 2000000 non_hh_weight 10000000
Crash log:
[ 690.654882] BUG: unable to handle kernel NULL pointer dereference at (null)
[ 690.655565] IP: hhf_destroy+0x48/0xbc
[ 690.655944] PGD 37345067
[ 690.655948] P4D 37345067
[ 690.656252] PUD 58402067
[ 690.656554] PMD 0
[ 690.656857]
[ 690.657362] Oops: 0000 [#1] SMP
[ 690.657696] Modules linked in:
[ 690.658032] CPU: 3 PID: 920 Comm: tc Not tainted 4.13.0-rc6+ #57
[ 690.658525] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140531_083030-gandalf 04/01/2014
[ 690.659255] task: ffff880058578000 task.stack: ffff88005acbc000
[ 690.659747] RIP: 0010:hhf_destroy+0x48/0xbc
[ 690.660146] RSP: 0018:ffff88005acbf9e0 EFLAGS: 00010246
[ 690.660601] RAX: 0000000000000000 RBX: 0000000000000020 RCX: 0000000000000000
[ 690.661155] RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffffffff821f63f0
[ 690.661710] RBP: ffff88005acbfa08 R08: ffffffff81b10a90 R09: 0000000000000000
[ 690.662267] R10: 00000000f42b7019 R11: ffff880058578000 R12: 00000000ffffffea
[ 690.662820] R13: ffff8800372f6400 R14: 0000000000000000 R15: 0000000000000000
[ 690.663769] FS: 00007f8ae5e8b740(0000) GS:ffff88005d980000(0000) knlGS:0000000000000000
[ 690.667069] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 690.667965] CR2: 0000000000000000 CR3: 0000000058523000 CR4: 00000000000406e0
[ 690.668918] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 690.669945] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 690.671003] Call Trace:
[ 690.671743] qdisc_create+0x377/0x3fd
[ 690.672534] tc_modify_qdisc+0x4d2/0x4fd
[ 690.673324] rtnetlink_rcv_msg+0x188/0x197
[ 690.674204] ? rcu_read_unlock+0x3e/0x5f
[ 690.675091] ? rtnl_newlink+0x729/0x729
[ 690.675877] netlink_rcv_skb+0x6c/0xce
[ 690.676648] rtnetlink_rcv+0x23/0x2a
[ 690.677405] netlink_unicast+0x103/0x181
[ 690.678179] netlink_sendmsg+0x326/0x337
[ 690.678958] sock_sendmsg_nosec+0x14/0x3f
[ 690.679743] sock_sendmsg+0x29/0x2e
[ 690.680506] ___sys_sendmsg+0x209/0x28b
[ 690.681283] ? __handle_mm_fault+0xc7d/0xdb1
[ 690.681915] ? check_chain_key+0xb0/0xfd
[ 690.682449] __sys_sendmsg+0x45/0x63
[ 690.682954] ? __sys_sendmsg+0x45/0x63
[ 690.683471] SyS_sendmsg+0x19/0x1b
[ 690.683974] entry_SYSCALL_64_fastpath+0x23/0xc2
[ 690.684516] RIP: 0033:0x7f8ae529d690
[ 690.685016] RSP: 002b:00007fff26d2d6b8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
[ 690.685931] RAX: ffffffffffffffda RBX: ffffffff810d278c RCX: 00007f8ae529d690
[ 690.686573] RDX: 0000000000000000 RSI: 00007fff26d2d700 RDI: 0000000000000003
[ 690.687047] RBP: ffff88005acbff98 R08: 0000000000000001 R09: 0000000000000000
[ 690.687519] R10: 00007fff26d2d480 R11: 0000000000000246 R12: 0000000000000002
[ 690.687996] R13: 0000000001258070 R14: 0000000000000001 R15: 0000000000000000
[ 690.688475] ? trace_hardirqs_off_caller+0xa7/0xcf
[ 690.688887] Code: 00 00 e8 2a 02 ae ff 49 8b bc 1d 60 02 00 00 48 83
c3 08 e8 19 02 ae ff 48 83 fb 20 75 dc 45 31 f6 4d 89 f7 4d 03 bd 20 02
00 00 <49> 8b 07 49 39 c7 75 24 49 83 c6 10 49 81 fe 00 40 00 00 75 e1
[ 690.690200] RIP: hhf_destroy+0x48/0xbc RSP: ffff88005acbf9e0
[ 690.690636] CR2: 0000000000000000
Fixes: 87b60cfacf9f ("net_sched: fix error recovery at qdisc creation")
Signed-off-by: Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
---
First I did it with the check in the for () conditional, but this is more
visible and explicit. Let me know if you'd like the shorter version. :-)
net/sched/sch_hhf.c | 20 +++++++++++---------
1 file changed, 11 insertions(+), 9 deletions(-)
diff --git a/net/sched/sch_hhf.c b/net/sched/sch_hhf.c
index 51d3ba682af9..931c6cc23ac2 100644
--- a/net/sched/sch_hhf.c
+++ b/net/sched/sch_hhf.c
@@ -477,15 +477,17 @@ static void hhf_destroy(struct Qdisc *sch)
kvfree(q->hhf_valid_bits[i]);
}
- for (i = 0; i < HH_FLOWS_CNT; i++) {
- struct hh_flow_state *flow, *next;
- struct list_head *head = &q->hh_flows[i];
-
- if (list_empty(head))
- continue;
- list_for_each_entry_safe(flow, next, head, flowchain) {
- list_del(&flow->flowchain);
- kfree(flow);
+ if (q->hh_flows) {
+ for (i = 0; i < HH_FLOWS_CNT; i++) {
+ struct hh_flow_state *flow, *next;
+ struct list_head *head = &q->hh_flows[i];
+
+ if (list_empty(head))
+ continue;
+ list_for_each_entry_safe(flow, next, head, flowchain) {
+ list_del(&flow->flowchain);
+ kfree(flow);
+ }
}
}
kvfree(q->hh_flows);
--
2.1.4
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