{"id":"AZL-72953","summary":"CVE-2025-38464 affecting package kernel for versions less than 5.15.200.1-1","details":"In the Linux kernel, the following vulnerability has been resolved:\n\ntipc: Fix use-after-free in tipc_conn_close().\n\nsyzbot reported a null-ptr-deref in tipc_conn_close() during netns\ndismantle. [0]\n\ntipc_topsrv_stop() iterates tipc_net(net)-\u003etopsrv-\u003econn_idr and calls\ntipc_conn_close() for each tipc_conn.\n\nThe problem is that tipc_conn_close() is called after releasing the\nIDR lock.\n\nAt the same time, there might be tipc_conn_recv_work() running and it\ncould call tipc_conn_close() for the same tipc_conn and release its\nlast -\u003ekref.\n\nOnce we release the IDR lock in tipc_topsrv_stop(), there is no\nguarantee that the tipc_conn is alive.\n\nLet's hold the ref before releasing the lock and put the ref after\ntipc_conn_close() in tipc_topsrv_stop().\n\n[0]:\nBUG: KASAN: use-after-free in tipc_conn_close+0x122/0x140 net/tipc/topsrv.c:165\nRead of size 8 at addr ffff888099305a08 by task kworker/u4:3/435\n\nCPU: 0 PID: 435 Comm: kworker/u4:3 Not tainted 4.19.204-syzkaller #0\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011\nWorkqueue: netns cleanup_net\nCall Trace:\n __dump_stack lib/dump_stack.c:77 [inline]\n dump_stack+0x1fc/0x2ef lib/dump_stack.c:118\n print_address_description.cold+0x54/0x219 mm/kasan/report.c:256\n kasan_report_error.cold+0x8a/0x1b9 mm/kasan/report.c:354\n kasan_report mm/kasan/report.c:412 [inline]\n __asan_report_load8_noabort+0x88/0x90 mm/kasan/report.c:433\n tipc_conn_close+0x122/0x140 net/tipc/topsrv.c:165\n tipc_topsrv_stop net/tipc/topsrv.c:701 [inline]\n tipc_topsrv_exit_net+0x27b/0x5c0 net/tipc/topsrv.c:722\n ops_exit_list+0xa5/0x150 net/core/net_namespace.c:153\n cleanup_net+0x3b4/0x8b0 net/core/net_namespace.c:553\n process_one_work+0x864/0x1570 kernel/workqueue.c:2153\n worker_thread+0x64c/0x1130 kernel/workqueue.c:2296\n kthread+0x33f/0x460 kernel/kthread.c:259\n ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415\n\nAllocated by task 23:\n kmem_cache_alloc_trace+0x12f/0x380 mm/slab.c:3625\n kmalloc include/linux/slab.h:515 [inline]\n kzalloc include/linux/slab.h:709 [inline]\n tipc_conn_alloc+0x43/0x4f0 net/tipc/topsrv.c:192\n tipc_topsrv_accept+0x1b5/0x280 net/tipc/topsrv.c:470\n process_one_work+0x864/0x1570 kernel/workqueue.c:2153\n worker_thread+0x64c/0x1130 kernel/workqueue.c:2296\n kthread+0x33f/0x460 kernel/kthread.c:259\n ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415\n\nFreed by task 23:\n __cache_free mm/slab.c:3503 [inline]\n kfree+0xcc/0x210 mm/slab.c:3822\n tipc_conn_kref_release net/tipc/topsrv.c:150 [inline]\n kref_put include/linux/kref.h:70 [inline]\n conn_put+0x2cd/0x3a0 net/tipc/topsrv.c:155\n process_one_work+0x864/0x1570 kernel/workqueue.c:2153\n worker_thread+0x64c/0x1130 kernel/workqueue.c:2296\n kthread+0x33f/0x460 kernel/kthread.c:259\n ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415\n\nThe buggy address belongs to the object at ffff888099305a00\n which belongs to the cache kmalloc-512 of size 512\nThe buggy address is located 8 bytes inside of\n 512-byte region [ffff888099305a00, ffff888099305c00)\nThe buggy address belongs to the page:\npage:ffffea000264c140 count:1 mapcount:0 mapping:ffff88813bff0940 index:0x0\nflags: 0xfff00000000100(slab)\nraw: 00fff00000000100 ffffea00028b6b88 ffffea0002cd2b08 ffff88813bff0940\nraw: 0000000000000000 ffff888099305000 0000000100000006 0000000000000000\npage dumped because: kasan: bad access detected\n\nMemory state around the buggy address:\n ffff888099305900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n ffff888099305980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc\n\u003effff888099305a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n                      ^\n ffff888099305a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n ffff888099305b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb","modified":"2026-04-01T05:22:13.919211Z","published":"2025-07-25T16:15:32Z","upstream":["CVE-2025-38464"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-38464"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:2","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.15.200.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-72953.json"}}],"schema_version":"1.7.5"}