When set multicast_query_interval to a large value, the local variable
'time' in br_multicast_send_query() may overflow. If the time is smaller
than jiffies, the timer will expire immediately, and then call mod_timer()
again, which creates a loop and may trigger the following soft lockup
issue:
watchdog: BUG: soft lockup - CPU#1 stuck for 221s! [rb_consumer:66]
CPU: 1 UID: 0 PID: 66 Comm: rb_consumer Not tainted 6.16.0+ #259 PREEMPT(none)
Call Trace:
<IRQ>
__netdev_alloc_skb+0x2e/0x3a0
br_ip6_multicast_alloc_query+0x212/0x1b70
__br_multicast_send_query+0x376/0xac0
br_multicast_send_query+0x299/0x510
br_multicast_query_expired.constprop.0+0x16d/0x1b0
call_timer_fn+0x3b/0x2a0
__run_timers+0x619/0x950
run_timer_softirq+0x11c/0x220
handle_softirqs+0x18e/0x560
__irq_exit_rcu+0x158/0x1a0
sysvec_apic_timer_interrupt+0x76/0x90
</IRQ>
This issue can be reproduced with:
ip link add br0 type bridge
echo 1 > /sys/class/net/br0/bridge/multicast_querier
echo 0xffffffffffffffff >
/sys/class/net/br0/bridge/multicast_query_interval
ip link set dev br0 up
Fix this by comparing expire time with jiffies, to avoid the timer loop.
Fixes: 7e4df51eb35d ("bridge: netlink: add support for igmp's intervals")
Signed-off-by: Wang Liang <wanglian...@huawei.com>
---
net/bridge/br_multicast.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index 1377f31b719c..631ae3b4c45d 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -1892,7 +1892,8 @@ static void br_multicast_send_query(struct
net_bridge_mcast *brmctx,
time += own_query->startup_sent < brmctx->multicast_startup_query_count
?
brmctx->multicast_startup_query_interval :
brmctx->multicast_query_interval;
- mod_timer(&own_query->timer, time);
+ if (time_is_after_jiffies(time))
+ mod_timer(&own_query->timer, time);
}
static void
--
2.34.1
