GHSA-33V4-FJQ4-GJWG
Vulnerability from github – Published: 2026-08-22 18:30 – Updated: 2026-08-25 06:31In the Linux kernel, the following vulnerability has been resolved:
bonding: alb: re-check primary_is_promisc under RTNL in bond_alb_monitor
bond_alb_monitor() reads primary_is_promisc under RCU, then drops RCU and takes RTNL via rtnl_trylock() before undoing the promiscuity it set on the active slave. In that window the active slave can change under RTNL (RTM_DELLINK -> __bond_release_one() -> bond_alb_handle_active_change()), which already drops the promiscuity and clears primary_is_promisc. The monitor still acts on the stale decision: if the slave was removed with no failover, curr_active_slave is now NULL and the deref faults; if it failed over, the stale dev_set_promiscuity(-1) underflows the new slave's promiscuity counter and pins it in IFF_PROMISC.
Oops: general protection fault, probably for non-canonical address ... KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] Workqueue: b42 bond_alb_monitor RIP: 0010:bond_alb_monitor (drivers/net/bonding/bond_alb.c:1600) process_one_work (kernel/workqueue.c:3322) worker_thread (kernel/workqueue.c:3486) kthread (kernel/kthread.c:436) ret_from_fork (arch/x86/kernel/process.c:158) Kernel panic - not syncing: Fatal exception
Re-check primary_is_promisc (and curr_active_slave) after taking RTNL so the monitor only undoes an increment it still owns. The other bonding monitors already re-read state under RTNL in their commit phase (bond_miimon_commit/bond_ab_arp_commit); bond_alb_monitor() was the only one acting on the pre-trylock decision.
{
"affected": [],
"aliases": [
"CVE-2026-74726"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-08-22T16:16:47Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbonding: alb: re-check primary_is_promisc under RTNL in bond_alb_monitor\n\nbond_alb_monitor() reads primary_is_promisc under RCU, then drops RCU and\ntakes RTNL via rtnl_trylock() before undoing the promiscuity it set on the\nactive slave. In that window the active slave can change under RTNL\n(RTM_DELLINK -\u003e __bond_release_one() -\u003e bond_alb_handle_active_change()),\nwhich already drops the promiscuity and clears primary_is_promisc. The\nmonitor still acts on the stale decision: if the slave was removed with no\nfailover, curr_active_slave is now NULL and the deref faults; if it failed\nover, the stale dev_set_promiscuity(-1) underflows the new slave\u0027s\npromiscuity counter and pins it in IFF_PROMISC.\n\n Oops: general protection fault, probably for non-canonical address ...\n KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]\n Workqueue: b42 bond_alb_monitor\n RIP: 0010:bond_alb_monitor (drivers/net/bonding/bond_alb.c:1600)\n process_one_work (kernel/workqueue.c:3322)\n worker_thread (kernel/workqueue.c:3486)\n kthread (kernel/kthread.c:436)\n ret_from_fork (arch/x86/kernel/process.c:158)\n Kernel panic - not syncing: Fatal exception\n\nRe-check primary_is_promisc (and curr_active_slave) after taking RTNL so\nthe monitor only undoes an increment it still owns. The other bonding\nmonitors already re-read state under RTNL in their commit phase\n(bond_miimon_commit/bond_ab_arp_commit); bond_alb_monitor() was the only\none acting on the pre-trylock decision.",
"id": "GHSA-33v4-fjq4-gjwg",
"modified": "2026-08-25T06:31:30Z",
"published": "2026-08-22T18:30:30Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-74726"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/09add8d5cfa9c46828f51eaad162c36e86366b71"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/257c4a3a34d8f51efb00f35375a0c6ce3c8f6ce2"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2faf75a8a06504071b4c0aea7e45a9cc49a4e187"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/683c6ba6e58e6ed1037831ea97dd58d9c0e76b8d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b82f51681a7a88c7d3c865e817a3340d42b5fa2a"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/dccec0227ed8d9e36936d66e256b957dc2858468"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/dd148539fb4741d01c06b7d2c8bd84b01920756c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f7668762bf5fd6db9397de5c0514407489d9d815"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H",
"type": "CVSS_V3"
}
]
}
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