{"id":"AZL-74366","summary":"CVE-2025-68801 affecting package kernel for versions less than 6.6.121.1-1","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nmlxsw: spectrum_router: Fix neighbour use-after-free\n\nWe sometimes observe use-after-free when dereferencing a neighbour [1].\nThe problem seems to be that the driver stores a pointer to the\nneighbour, but without holding a reference on it. A reference is only\ntaken when the neighbour is used by a nexthop.\n\nFix by simplifying the reference counting scheme. Always take a\nreference when storing a neighbour pointer in a neighbour entry. Avoid\ntaking a referencing when the neighbour is used by a nexthop as the\nneighbour entry associated with the nexthop already holds a reference.\n\nTested by running the test that uncovered the problem over 300 times.\nWithout this patch the problem was reproduced after a handful of\niterations.\n\n[1]\nBUG: KASAN: slab-use-after-free in mlxsw_sp_neigh_entry_update+0x2d4/0x310\nRead of size 8 at addr ffff88817f8e3420 by task ip/3929\n\nCPU: 3 UID: 0 PID: 3929 Comm: ip Not tainted 6.18.0-rc4-virtme-g36b21a067510 #3 PREEMPT(full)\nHardware name: Nvidia SN5600/VMOD0013, BIOS 5.13 05/31/2023\nCall Trace:\n \u003cTASK\u003e\n dump_stack_lvl+0x6f/0xa0\n print_address_description.constprop.0+0x6e/0x300\n print_report+0xfc/0x1fb\n kasan_report+0xe4/0x110\n mlxsw_sp_neigh_entry_update+0x2d4/0x310\n mlxsw_sp_router_rif_gone_sync+0x35f/0x510\n mlxsw_sp_rif_destroy+0x1ea/0x730\n mlxsw_sp_inetaddr_port_vlan_event+0xa1/0x1b0\n __mlxsw_sp_inetaddr_lag_event+0xcc/0x130\n __mlxsw_sp_inetaddr_event+0xf5/0x3c0\n mlxsw_sp_router_netdevice_event+0x1015/0x1580\n notifier_call_chain+0xcc/0x150\n call_netdevice_notifiers_info+0x7e/0x100\n __netdev_upper_dev_unlink+0x10b/0x210\n netdev_upper_dev_unlink+0x79/0xa0\n vrf_del_slave+0x18/0x50\n do_set_master+0x146/0x7d0\n do_setlink.isra.0+0x9a0/0x2880\n rtnl_newlink+0x637/0xb20\n rtnetlink_rcv_msg+0x6fe/0xb90\n netlink_rcv_skb+0x123/0x380\n netlink_unicast+0x4a3/0x770\n netlink_sendmsg+0x75b/0xc90\n __sock_sendmsg+0xbe/0x160\n ____sys_sendmsg+0x5b2/0x7d0\n ___sys_sendmsg+0xfd/0x180\n __sys_sendmsg+0x124/0x1c0\n do_syscall_64+0xbb/0xfd0\n entry_SYSCALL_64_after_hwframe+0x4b/0x53\n[...]\n\nAllocated by task 109:\n kasan_save_stack+0x30/0x50\n kasan_save_track+0x14/0x30\n __kasan_kmalloc+0x7b/0x90\n __kmalloc_noprof+0x2c1/0x790\n neigh_alloc+0x6af/0x8f0\n ___neigh_create+0x63/0xe90\n mlxsw_sp_nexthop_neigh_init+0x430/0x7e0\n mlxsw_sp_nexthop_type_init+0x212/0x960\n mlxsw_sp_nexthop6_group_info_init.constprop.0+0x81f/0x1280\n mlxsw_sp_nexthop6_group_get+0x392/0x6a0\n mlxsw_sp_fib6_entry_create+0x46a/0xfd0\n mlxsw_sp_router_fib6_replace+0x1ed/0x5f0\n mlxsw_sp_router_fib6_event_work+0x10a/0x2a0\n process_one_work+0xd57/0x1390\n worker_thread+0x4d6/0xd40\n kthread+0x355/0x5b0\n ret_from_fork+0x1d4/0x270\n ret_from_fork_asm+0x11/0x20\n\nFreed by task 154:\n kasan_save_stack+0x30/0x50\n kasan_save_track+0x14/0x30\n __kasan_save_free_info+0x3b/0x60\n __kasan_slab_free+0x43/0x70\n kmem_cache_free_bulk.part.0+0x1eb/0x5e0\n kvfree_rcu_bulk+0x1f2/0x260\n kfree_rcu_work+0x130/0x1b0\n process_one_work+0xd57/0x1390\n worker_thread+0x4d6/0xd40\n kthread+0x355/0x5b0\n ret_from_fork+0x1d4/0x270\n ret_from_fork_asm+0x11/0x20\n\nLast potentially related work creation:\n kasan_save_stack+0x30/0x50\n kasan_record_aux_stack+0x8c/0xa0\n kvfree_call_rcu+0x93/0x5b0\n mlxsw_sp_router_neigh_event_work+0x67d/0x860\n process_one_work+0xd57/0x1390\n worker_thread+0x4d6/0xd40\n kthread+0x355/0x5b0\n ret_from_fork+0x1d4/0x270\n ret_from_fork_asm+0x11/0x20","modified":"2026-04-01T05:22:43.017745Z","published":"2026-01-13T16:16:02Z","upstream":["CVE-2025-68801"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-68801"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.6.121.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-74366.json"}}],"schema_version":"1.7.5"}