CVE-2025-38464

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> tipc: Fix use-after-free in tipc_conn_close().<br /> <br /> syzbot reported a null-ptr-deref in tipc_conn_close() during netns<br /> dismantle. [0]<br /> <br /> tipc_topsrv_stop() iterates tipc_net(net)-&gt;topsrv-&gt;conn_idr and calls<br /> tipc_conn_close() for each tipc_conn.<br /> <br /> The problem is that tipc_conn_close() is called after releasing the<br /> IDR lock.<br /> <br /> At the same time, there might be tipc_conn_recv_work() running and it<br /> could call tipc_conn_close() for the same tipc_conn and release its<br /> last -&gt;kref.<br /> <br /> Once we release the IDR lock in tipc_topsrv_stop(), there is no<br /> guarantee that the tipc_conn is alive.<br /> <br /> Let&amp;#39;s hold the ref before releasing the lock and put the ref after<br /> tipc_conn_close() in tipc_topsrv_stop().<br /> <br /> [0]:<br /> BUG: KASAN: use-after-free in tipc_conn_close+0x122/0x140 net/tipc/topsrv.c:165<br /> Read of size 8 at addr ffff888099305a08 by task kworker/u4:3/435<br /> <br /> CPU: 0 PID: 435 Comm: kworker/u4:3 Not tainted 4.19.204-syzkaller #0<br /> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011<br /> Workqueue: netns cleanup_net<br /> Call Trace:<br /> __dump_stack lib/dump_stack.c:77 [inline]<br /> dump_stack+0x1fc/0x2ef lib/dump_stack.c:118<br /> print_address_description.cold+0x54/0x219 mm/kasan/report.c:256<br /> kasan_report_error.cold+0x8a/0x1b9 mm/kasan/report.c:354<br /> kasan_report mm/kasan/report.c:412 [inline]<br /> __asan_report_load8_noabort+0x88/0x90 mm/kasan/report.c:433<br /> tipc_conn_close+0x122/0x140 net/tipc/topsrv.c:165<br /> tipc_topsrv_stop net/tipc/topsrv.c:701 [inline]<br /> tipc_topsrv_exit_net+0x27b/0x5c0 net/tipc/topsrv.c:722<br /> ops_exit_list+0xa5/0x150 net/core/net_namespace.c:153<br /> cleanup_net+0x3b4/0x8b0 net/core/net_namespace.c:553<br /> process_one_work+0x864/0x1570 kernel/workqueue.c:2153<br /> worker_thread+0x64c/0x1130 kernel/workqueue.c:2296<br /> kthread+0x33f/0x460 kernel/kthread.c:259<br /> ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415<br /> <br /> Allocated by task 23:<br /> kmem_cache_alloc_trace+0x12f/0x380 mm/slab.c:3625<br /> kmalloc include/linux/slab.h:515 [inline]<br /> kzalloc include/linux/slab.h:709 [inline]<br /> tipc_conn_alloc+0x43/0x4f0 net/tipc/topsrv.c:192<br /> tipc_topsrv_accept+0x1b5/0x280 net/tipc/topsrv.c:470<br /> process_one_work+0x864/0x1570 kernel/workqueue.c:2153<br /> worker_thread+0x64c/0x1130 kernel/workqueue.c:2296<br /> kthread+0x33f/0x460 kernel/kthread.c:259<br /> ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415<br /> <br /> Freed by task 23:<br /> __cache_free mm/slab.c:3503 [inline]<br /> kfree+0xcc/0x210 mm/slab.c:3822<br /> tipc_conn_kref_release net/tipc/topsrv.c:150 [inline]<br /> kref_put include/linux/kref.h:70 [inline]<br /> conn_put+0x2cd/0x3a0 net/tipc/topsrv.c:155<br /> process_one_work+0x864/0x1570 kernel/workqueue.c:2153<br /> worker_thread+0x64c/0x1130 kernel/workqueue.c:2296<br /> kthread+0x33f/0x460 kernel/kthread.c:259<br /> ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415<br /> <br /> The buggy address belongs to the object at ffff888099305a00<br /> which belongs to the cache kmalloc-512 of size 512<br /> The buggy address is located 8 bytes inside of<br /> 512-byte region [ffff888099305a00, ffff888099305c00)<br /> The buggy address belongs to the page:<br /> page:ffffea000264c140 count:1 mapcount:0 mapping:ffff88813bff0940 index:0x0<br /> flags: 0xfff00000000100(slab)<br /> raw: 00fff00000000100 ffffea00028b6b88 ffffea0002cd2b08 ffff88813bff0940<br /> raw: 0000000000000000 ffff888099305000 0000000100000006 0000000000000000<br /> page dumped because: kasan: bad access detected<br /> <br /> Memory state around the buggy address:<br /> ffff888099305900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb<br /> ffff888099305980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc<br /> &gt;ffff888099305a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb<br /> ^<br /> ffff888099305a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb<br /> ffff888099305b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb