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* [PATCH net] net: sched: fix NULL pointer dereference in mq_attach
@ 2023-05-27  9:37 Zhengchao Shao
  2023-05-28 19:05 ` Jamal Hadi Salim
                   ` (3 more replies)
  0 siblings, 4 replies; 15+ messages in thread
From: Zhengchao Shao @ 2023-05-27  9:37 UTC (permalink / raw)
  To: netdev, jhs, xiyou.wangcong, jiri, davem, edumazet, kuba, pabeni
  Cc: weiyongjun1, yuehaibing, shaozhengchao, wanghai38

When use the following command to test:
1)ip link add bond0 type bond
2)ip link set bond0 up
3)tc qdisc add dev bond0 root handle ffff: mq
4)tc qdisc replace dev bond0 parent ffff:fff1 handle ffff: mq

The kernel reports NULL pointer dereference issue. The stack information
is as follows:
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
Internal error: Oops: 0000000096000006 [#1] SMP
Modules linked in:
pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : mq_attach+0x44/0xa0
lr : qdisc_graft+0x20c/0x5cc
sp : ffff80000e2236a0
x29: ffff80000e2236a0 x28: ffff0000c0e59d80 x27: ffff0000c0be19c0
x26: ffff0000cae3e800 x25: 0000000000000010 x24: 00000000fffffff1
x23: 0000000000000000 x22: ffff0000cae3e800 x21: ffff0000c9df4000
x20: ffff0000c9df4000 x19: 0000000000000000 x18: ffff80000a934000
x17: ffff8000f5b56000 x16: ffff80000bb08000 x15: 0000000000000000
x14: 0000000000000000 x13: 6b6b6b6b6b6b6b6b x12: 6b6b6b6b00000001
x11: 0000000000000000 x10: 0000000000000000 x9 : 0000000000000000
x8 : ffff0000c0be0730 x7 : bbbbbbbbbbbbbbbb x6 : 0000000000000008
x5 : ffff0000cae3e864 x4 : 0000000000000000 x3 : 0000000000000001
x2 : 0000000000000001 x1 : ffff8000090bc23c x0 : 0000000000000000
Call trace:
mq_attach+0x44/0xa0
qdisc_graft+0x20c/0x5cc
tc_modify_qdisc+0x1c4/0x664
rtnetlink_rcv_msg+0x354/0x440
netlink_rcv_skb+0x64/0x144
rtnetlink_rcv+0x28/0x34
netlink_unicast+0x1e8/0x2a4
netlink_sendmsg+0x308/0x4a0
sock_sendmsg+0x64/0xac
____sys_sendmsg+0x29c/0x358
___sys_sendmsg+0x90/0xd0
__sys_sendmsg+0x7c/0xd0
__arm64_sys_sendmsg+0x2c/0x38
invoke_syscall+0x54/0x114
el0_svc_common.constprop.1+0x90/0x174
do_el0_svc+0x3c/0xb0
el0_svc+0x24/0xec
el0t_64_sync_handler+0x90/0xb4
el0t_64_sync+0x174/0x178

This is because when mq is added for the first time, qdiscs in mq is set
to NULL in mq_attach(). Therefore, when replacing mq after adding mq, we
need to initialize qdiscs in the mq before continuing to graft. Otherwise,
it will couse NULL pointer dereference issue in mq_attach(). And the same
issue will occur in the attach functions of mqprio, taprio and htb.
ffff:fff1 means that the repalce qdisc is ingress. Ingress does not allow
any qdisc to be attached. Therefore, ffff:fff1 is incorrectly used, and
the command should be dropped.

Fixes: 6ec1c69a8f64 ("net_sched: add classful multiqueue dummy scheduler")
Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>
---
 net/sched/sch_api.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index fdb8f429333d..dbc9cf5eea89 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -1596,6 +1596,10 @@ static int tc_modify_qdisc(struct sk_buff *skb, struct nlmsghdr *n,
 					NL_SET_ERR_MSG(extack, "Qdisc parent/child loop detected");
 					return -ELOOP;
 				}
+				if (clid == TC_H_INGRESS) {
+					NL_SET_ERR_MSG(extack, "Ingress cannot graft directly");
+					return -EINVAL;
+				}
 				qdisc_refcount_inc(q);
 				goto graft;
 			} else {
-- 
2.34.1


^ permalink raw reply related	[flat|nested] 15+ messages in thread

end of thread, other threads:[~2023-05-31  6:40 UTC | newest]

Thread overview: 15+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2023-05-27  9:37 [PATCH net] net: sched: fix NULL pointer dereference in mq_attach Zhengchao Shao
2023-05-28 19:05 ` Jamal Hadi Salim
2023-05-29  1:10   ` shaozhengchao
2023-05-29  8:59     ` Peilin Ye
2023-05-29 10:18       ` shaozhengchao
2023-05-29 13:53       ` Jamal Hadi Salim
2023-05-30  0:17         ` Peilin Ye
2023-05-30  2:45           ` shaozhengchao
2023-05-30 10:16           ` Paolo Abeni
2023-05-31  0:35             ` Peilin Ye
2023-05-31  1:00               ` shaozhengchao
2023-05-31  0:43             ` Jamal Hadi Salim
2023-05-30  1:07 ` Peilin Ye
2023-05-31  0:50 ` Jamal Hadi Salim
2023-05-31  6:40 ` patchwork-bot+netdevbpf

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