ghsa-4vq6-c2m7-38vx
Vulnerability from github
Published
2025-09-11 18:35
Modified
2025-09-11 18:35
Details

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

net: bridge: fix soft lockup in br_multicast_query_expired()

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: __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

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

The multicast_startup_query_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.

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{
  "affected": [],
  "aliases": [
    "CVE-2025-39773"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-09-11T17:15:43Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: bridge: fix soft lockup in br_multicast_query_expired()\n\nWhen set multicast_query_interval to a large value, the local variable\n\u0027time\u0027 in br_multicast_send_query() may overflow. If the time is smaller\nthan jiffies, the timer will expire immediately, and then call mod_timer()\nagain, which creates a loop and may trigger the following soft lockup\nissue.\n\n  watchdog: BUG: soft lockup - CPU#1 stuck for 221s! [rb_consumer:66]\n  CPU: 1 UID: 0 PID: 66 Comm: rb_consumer Not tainted 6.16.0+ #259 PREEMPT(none)\n  Call Trace:\n   \u003cIRQ\u003e\n   __netdev_alloc_skb+0x2e/0x3a0\n   br_ip6_multicast_alloc_query+0x212/0x1b70\n   __br_multicast_send_query+0x376/0xac0\n   br_multicast_send_query+0x299/0x510\n   br_multicast_query_expired.constprop.0+0x16d/0x1b0\n   call_timer_fn+0x3b/0x2a0\n   __run_timers+0x619/0x950\n   run_timer_softirq+0x11c/0x220\n   handle_softirqs+0x18e/0x560\n   __irq_exit_rcu+0x158/0x1a0\n   sysvec_apic_timer_interrupt+0x76/0x90\n   \u003c/IRQ\u003e\n\nThis issue can be reproduced with:\n  ip link add br0 type bridge\n  echo 1 \u003e /sys/class/net/br0/bridge/multicast_querier\n  echo 0xffffffffffffffff \u003e\n  \t/sys/class/net/br0/bridge/multicast_query_interval\n  ip link set dev br0 up\n\nThe multicast_startup_query_interval can also cause this issue. Similar to\nthe commit 99b40610956a (\"net: bridge: mcast: add and enforce query\ninterval minimum\"), add check for the query interval maximum to fix this\nissue.",
  "id": "GHSA-4vq6-c2m7-38vx",
  "modified": "2025-09-11T18:35:52Z",
  "published": "2025-09-11T18:35:52Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-39773"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/34171b9e53bd1dc264f5556579f2b04f04435c73"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/43e281fde5e76a866a4d10780c35023f16c0e432"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5bf5fce8a0c2a70d063af778fdb5b27238174cdd"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/96476b043efb86a94f2badd260f7f99c97bd5893"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/bdb19cd0de739870bb3494c815138b9dc30875c4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d1547bf460baec718b3398365f8de33d25c5f36f"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}


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