{"id":"CVE-2026-74726","summary":"bonding: alb: re-check primary_is_promisc under RTNL in bond_alb_monitor","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's\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.","modified":"2026-08-23T03:53:41.253085059Z","published":"2026-08-22T15:33:17.128Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74726.json","cna_assigner":"Linux"},"references":[{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"},{"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"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74726.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74726"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"d0e81b7e2246a41d068ecaf15aac9de570816d63"},{"fixed":"f7668762bf5fd6db9397de5c0514407489d9d815"},{"fixed":"09add8d5cfa9c46828f51eaad162c36e86366b71"},{"fixed":"b82f51681a7a88c7d3c865e817a3340d42b5fa2a"},{"fixed":"dd148539fb4741d01c06b7d2c8bd84b01920756c"},{"fixed":"dccec0227ed8d9e36936d66e256b957dc2858468"},{"fixed":"2faf75a8a06504071b4c0aea7e45a9cc49a4e187"},{"fixed":"257c4a3a34d8f51efb00f35375a0c6ce3c8f6ce2"},{"fixed":"683c6ba6e58e6ed1037831ea97dd58d9c0e76b8d"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74726.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.6.24"},{"fixed":"5.10.265"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.216"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.183"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.152"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.104"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.45"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.9"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74726.json"}}],"schema_version":"1.9.0"}