This is a note to let you know that I've just added the patch titled
net: sched: fix NULL pointer dereference in mq_attach
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
net-sched-fix-null-pointer-dereference-in-mq_attach.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 6489af958b1bdce92b4508ecfe357a4479a9c176
Author: Zhengchao Shao <shaozhengchao@xxxxxxxxxx>
Date: Sat May 27 17:37:47 2023 +0800
net: sched: fix NULL pointer dereference in mq_attach
[ Upstream commit 36eec020fab668719b541f34d97f44e232ffa165 ]
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@xxxxxxxxxx>
Tested-by: Peilin Ye <peilin.ye@xxxxxxxxxxxxx>
Acked-by: Jamal Hadi Salim <jhs@xxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20230527093747.3583502-1-shaozhengchao@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 8045562011819..5a0e71873e24b 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -1524,6 +1524,10 @@ 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 {
