> On May 30, 2018, at 11:17 AM, Stefan Hajnoczi <stefa...@redhat.com> wrote: > > On Sun, May 27, 2018 at 11:29:45PM +0800, Hangbin Liu wrote: >> Hmm...Although I won't reproduce this bug with my reproducer after >> apply my patch. I could still get a similiar issue with syzkaller sock vnet >> test. >> >> It looks this patch is not complete. Here is the KASAN call trace with my >> patch. >> I can also reproduce it without my patch. > > Seems like a race between vmci_datagram_destroy_handle() and the > delayed callback, vmci_transport_recv_dgram_cb(). > > I don't know the VMCI transport well so I'll leave this to Jorgen.
Yes, it looks like we are calling the delayed callback after we return from vmci_datagram_destroy_handle(). I’ll take a closer look at the VMCI side here - the refcounting of VMCI datagram endpoints should guard against this, since the delayed callback does a get on the datagram resource, so this could a VMCI driver issue, and not a problem in the VMCI transport for AF_VSOCK. > >> ================================================================== >> BUG: KASAN: use-after-free in vmci_transport_allow_dgram.part.7+0x155/0x1a0 >> [vmw_vsock_vmci_transport] >> Read of size 4 at addr ffff880026a3a914 by task kworker/0:2/96 >> >> CPU: 0 PID: 96 Comm: kworker/0:2 Not tainted 4.17.0-rc6.vsock+ #28 >> Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011 >> Workqueue: events dg_delayed_dispatch [vmw_vmci] >> Call Trace: >> __dump_stack lib/dump_stack.c:77 [inline] >> dump_stack+0xdd/0x18e lib/dump_stack.c:113 >> print_address_description+0x7a/0x3e0 mm/kasan/report.c:256 >> kasan_report_error mm/kasan/report.c:354 [inline] >> kasan_report+0x1dd/0x460 mm/kasan/report.c:412 >> vmci_transport_allow_dgram.part.7+0x155/0x1a0 [vmw_vsock_vmci_transport] >> vmci_transport_recv_dgram_cb+0x5d/0x200 [vmw_vsock_vmci_transport] >> dg_delayed_dispatch+0x99/0x1b0 [vmw_vmci] >> process_one_work+0xa4e/0x1720 kernel/workqueue.c:2145 >> worker_thread+0x1df/0x1400 kernel/workqueue.c:2279 >> kthread+0x343/0x4b0 kernel/kthread.c:240 >> ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:412 >> >> Allocated by task 2684: >> set_track mm/kasan/kasan.c:460 [inline] >> kasan_kmalloc+0xa0/0xd0 mm/kasan/kasan.c:553 >> slab_post_alloc_hook mm/slab.h:444 [inline] >> slab_alloc_node mm/slub.c:2741 [inline] >> slab_alloc mm/slub.c:2749 [inline] >> kmem_cache_alloc+0x105/0x330 mm/slub.c:2754 >> sk_prot_alloc+0x6a/0x2c0 net/core/sock.c:1468 >> sk_alloc+0xc9/0xbb0 net/core/sock.c:1528 >> __vsock_create+0xc8/0x9b0 [vsock] >> vsock_create+0xfd/0x1a0 [vsock] >> __sock_create+0x310/0x690 net/socket.c:1285 >> sock_create net/socket.c:1325 [inline] >> __sys_socket+0x101/0x240 net/socket.c:1355 >> __do_sys_socket net/socket.c:1364 [inline] >> __se_sys_socket net/socket.c:1362 [inline] >> __x64_sys_socket+0x7d/0xd0 net/socket.c:1362 >> do_syscall_64+0x175/0x630 arch/x86/entry/common.c:287 >> entry_SYSCALL_64_after_hwframe+0x44/0xa9 >> >> Freed by task 2684: >> set_track mm/kasan/kasan.c:460 [inline] >> __kasan_slab_free+0x130/0x180 mm/kasan/kasan.c:521 >> slab_free_hook mm/slub.c:1388 [inline] >> slab_free_freelist_hook mm/slub.c:1415 [inline] >> slab_free mm/slub.c:2988 [inline] >> kmem_cache_free+0xce/0x410 mm/slub.c:3004 >> sk_prot_free net/core/sock.c:1509 [inline] >> __sk_destruct+0x629/0x940 net/core/sock.c:1593 >> sk_destruct+0x4e/0x90 net/core/sock.c:1601 >> __sk_free+0xd3/0x320 net/core/sock.c:1612 >> sk_free+0x2a/0x30 net/core/sock.c:1623 >> __vsock_release+0x431/0x610 [vsock] >> vsock_release+0x3c/0xc0 [vsock] >> sock_release+0x91/0x200 net/socket.c:594 >> sock_close+0x17/0x20 net/socket.c:1149 >> __fput+0x368/0xa20 fs/file_table.c:209 >> task_work_run+0x1c5/0x2a0 kernel/task_work.c:113 >> exit_task_work include/linux/task_work.h:22 [inline] >> do_exit+0x1876/0x26c0 kernel/exit.c:865 >> do_group_exit+0x159/0x3e0 kernel/exit.c:968 >> get_signal+0x65a/0x1780 kernel/signal.c:2482 >> do_signal+0xa4/0x1fe0 arch/x86/kernel/signal.c:810 >> exit_to_usermode_loop+0x1b8/0x260 arch/x86/entry/common.c:162 >> prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline] >> syscall_return_slowpath arch/x86/entry/common.c:265 [inline] >> do_syscall_64+0x505/0x630 arch/x86/entry/common.c:290 >> entry_SYSCALL_64_after_hwframe+0x44/0xa9 >> >> The buggy address belongs to the object at ffff880026a3a600 >> which belongs to the cache AF_VSOCK of size 1056 >> The buggy address is located 788 bytes inside of >> 1056-byte region [ffff880026a3a600, ffff880026a3aa20) >> The buggy address belongs to the page: >> page:ffffea00009a8e00 count:1 mapcount:0 mapping:0000000000000000 index:0x0 >> compound_mapcount: 0 >> flags: 0xfffffc0008100(slab|head) >> raw: 000fffffc0008100 0000000000000000 0000000000000000 00000001000d000d >> raw: dead000000000100 dead000000000200 ffff880034471a40 0000000000000000 >> page dumped because: kasan: bad access detected >> >> Memory state around the buggy address: >> ffff880026a3a800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >> ffff880026a3a880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >>> ffff880026a3a900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >> ^ >> ffff880026a3a980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >> ffff880026a3aa00: fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc >> ==================================================================