From 84c3848951cc4dd28798f5b251026d85f8498867 Mon Sep 17 00:00:00 2001
From: Zhengchao Shao <shaozhengchao@huawei.com>
Date: Thu, 23 Nov 2023 15:13:14 +0800
Subject: [PATCH] ipv4: igmp: fix refcnt uaf issue when receiving igmp query
packet
Git-commit: e2b706c691905fe78468c361aaabc719d0a496f1
Patch-mainline: v6.7-rc4
References: bsc#1218253 CVE-2023-6932
When I perform the following test operations:
1.ip link add br0 type bridge
2.brctl addif br0 eth0
3.ip addr add 239.0.0.1/32 dev eth0
4.ip addr add 239.0.0.1/32 dev br0
5.ip addr add 224.0.0.1/32 dev br0
6.while ((1))
do
ifconfig br0 up
ifconfig br0 down
done
7.send IGMPv2 query packets to port eth0 continuously. For example,
./mausezahn ethX -c 0 "01 00 5e 00 00 01 00 72 19 88 aa 02 08 00 45 00 00
1c 00 01 00 00 01 02 0e 7f c0 a8 0a b7 e0 00 00 01 11 64 ee 9b 00 00 00 00"
The preceding tests may trigger the refcnt uaf issue of the mc list. The
stack is as follows:
refcount_t: addition on 0; use-after-free.
WARNING: CPU: 21 PID: 144 at lib/refcount.c:25 refcount_warn_saturate (lib/refcount.c:25)
CPU: 21 PID: 144 Comm: ksoftirqd/21 Kdump: loaded Not tainted 6.7.0-rc1-next-20231117-dirty #80
Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
RIP: 0010:refcount_warn_saturate (lib/refcount.c:25)
RSP: 0018:ffffb68f00657910 EFLAGS: 00010286
RAX: 0000000000000000 RBX: ffff8a00c3bf96c0 RCX: ffff8a07b6160908
RDX: 00000000ffffffd8 RSI: 0000000000000027 RDI: ffff8a07b6160900
RBP: ffff8a00cba36862 R08: 0000000000000000 R09: 00000000ffff7fff
R10: ffffb68f006577c0 R11: ffffffffb0fdcdc8 R12: ffff8a00c3bf9680
R13: ffff8a00c3bf96f0 R14: 0000000000000000 R15: ffff8a00d8766e00
FS: 0000000000000000(0000) GS:ffff8a07b6140000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055f10b520b28 CR3: 000000039741a000 CR4: 00000000000006f0
Call Trace:
<TASK>
igmp_heard_query (net/ipv4/igmp.c:1068)
igmp_rcv (net/ipv4/igmp.c:1132)
ip_protocol_deliver_rcu (net/ipv4/ip_input.c:205)
ip_local_deliver_finish (net/ipv4/ip_input.c:234)
__netif_receive_skb_one_core (net/core/dev.c:5529)
netif_receive_skb_internal (net/core/dev.c:5729)
netif_receive_skb (net/core/dev.c:5788)
br_handle_frame_finish (net/bridge/br_input.c:216)
nf_hook_bridge_pre (net/bridge/br_input.c:294)
__netif_receive_skb_core (net/core/dev.c:5423)
__netif_receive_skb_list_core (net/core/dev.c:5606)
__netif_receive_skb_list (net/core/dev.c:5674)
netif_receive_skb_list_internal (net/core/dev.c:5764)
napi_gro_receive (net/core/gro.c:609)
e1000_clean_rx_irq (drivers/net/ethernet/intel/e1000/e1000_main.c:4467)
e1000_clean (drivers/net/ethernet/intel/e1000/e1000_main.c:3805)
__napi_poll (net/core/dev.c:6533)
net_rx_action (net/core/dev.c:6735)
__do_softirq (kernel/softirq.c:554)
run_ksoftirqd (kernel/softirq.c:913)
smpboot_thread_fn (kernel/smpboot.c:164)
kthread (kernel/kthread.c:388)
ret_from_fork (arch/x86/kernel/process.c:153)
ret_from_fork_asm (arch/x86/entry/entry_64.S:250)
</TASK>
The root causes are as follows:
Thread A Thread B
... netif_receive_skb
br_dev_stop ...
br_multicast_leave_snoopers ...
__ip_mc_dec_group ...
__igmp_group_dropped igmp_rcv
igmp_stop_timer igmp_heard_query //ref = 1
ip_ma_put igmp_mod_timer
refcount_dec_and_test igmp_start_timer //ref = 0
... refcount_inc //ref increases from 0
When the device receives an IGMPv2 Query message, it starts the timer
immediately, regardless of whether the device is running. If the device is
down and has left the multicast group, it will cause the mc list refcount
uaf issue.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Denis Kirjanov <denis.kirjanov@suse.com>
---
net/ipv4/igmp.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index df574049d33c..34d5e14d600a 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -218,8 +218,10 @@ static void igmp_start_timer(struct ip_mc_list *im, int max_delay)
int tv = prandom_u32() % max_delay;
im->tm_running = 1;
- if (!mod_timer(&im->timer, jiffies+tv+2))
- refcount_inc(&im->refcnt);
+ if (refcount_inc_not_zero(&im->refcnt)) {
+ if (mod_timer(&im->timer, jiffies + tv + 2))
+ ip_ma_put(im);
+ }
}
static void igmp_gq_start_timer(struct in_device *in_dev)
--
2.16.4