CVE-2025-39773

In the Linux kernel, the following vulnerability has been resolved:

net: bridge: fix soft lockup in brmulticastquery_expired()

When set multicastqueryinterval to a large value, the local variable 'time' in brmulticastsendquery() may overflow. If the time is smaller than jiffies, the timer will expire immediately, and then call modtimer() again, which creates a loop and may trigger the following soft lockup issue.

watchdog: BUG: soft lockup - CPU#1 stuck for 221s! [rbconsumer:66] CPU: 1 UID: 0 PID: 66 Comm: rbconsumer Not tainted 6.16.0+ #259 PREEMPT(none) Call Trace: <IRQ> __netdevallocskb+0x2e/0x3a0 brip6multicastallocquery+0x212/0x1b70 __brmulticastsendquery+0x376/0xac0 brmulticastsendquery+0x299/0x510 brmulticastqueryexpired.constprop.0+0x16d/0x1b0 calltimer_fn+0x3b/0x2a0 __runtimers+0x619/0x950 runtimersoftirq+0x11c/0x220 handlesoftirqs+0x18e/0x560 _irqexitrcu+0x158/0x1a0 sysvecapictimerinterrupt+0x76/0x90 </IRQ>

This issue can be reproduced with: ip link add br0 type bridge echo 1 > /sys/class/net/br0/bridge/multicastquerier echo 0xffffffffffffffff > /sys/class/net/br0/bridge/multicastquery_interval ip link set dev br0 up

The multicaststartupquery_interval can also cause this issue. Similar to the commit 99b40610956a ("net: bridge: mcast: add and enforce query interval minimum"), add check for the query interval maximum to fix this issue.