> On Apr 30, 2018, at 9:34 AM, syzbot <syzbot+27db1f90e2b972a5f2d3@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > Hello, > > syzbot hit the following crash on bpf-next commit > f60ad0a0c441530280a4918eca781a6a94dffa50 (Sun Apr 29 15:45:55 2018 +0000) > Merge branch 'bpf_get_stack' > syzbot dashboard link: https://syzkaller.appspot.com/bug?extid=27db1f90e2b972a5f2d3 > > Unfortunately, I don't have any reproducer for this crash yet. > Raw console output: https://syzkaller.appspot.com/x/log.txt?id=6741221342969856 > Kernel config: https://syzkaller.appspot.com/x/.config?id=4410550353033654931 > compiler: gcc (GCC) 8.0.1 20180413 (experimental) > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+27db1f90e2b972a5f2d3@xxxxxxxxxxxxxxxxxxxxxxxxx > It will help syzbot understand when the bug is fixed. See footer for details. > If you forward the report, please keep this part and the footer. > > rpcbind: RPC call returned error 22 > rpcbind: RPC call returned error 22 > rpcbind: RPC call returned error 22 > rpcbind: RPC call returned error 22 > ================================================================== > BUG: KASAN: use-after-free in strlen+0x83/0xa0 lib/string.c:482 > Read of size 1 at addr ffff8801d6f0a1c0 by task syz-executor7/5079 > > CPU: 1 PID: 5079 Comm: syz-executor7 Not tainted 4.17.0-rc2+ #16 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > Call Trace: > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0x1b9/0x294 lib/dump_stack.c:113 > print_address_description+0x6c/0x20b mm/kasan/report.c:256 > kasan_report_error mm/kasan/report.c:354 [inline] > kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412 > __asan_report_load1_noabort+0x14/0x20 mm/kasan/report.c:430 > strlen+0x83/0xa0 lib/string.c:482 > trace_event_get_offsets_rpc_stats_latency include/trace/events/sunrpc.h:215 [inline] > perf_trace_rpc_stats_latency+0x318/0x10d0 include/trace/events/sunrpc.h:215 > trace_rpc_stats_latency include/trace/events/sunrpc.h:215 [inline] > rpc_count_iostats_metrics+0x594/0x8a0 net/sunrpc/stats.c:182 > rpc_count_iostats+0x76/0x90 net/sunrpc/stats.c:195 > xprt_release+0xa3b/0x1110 net/sunrpc/xprt.c:1351 > rpc_release_resources_task+0x20/0xa0 net/sunrpc/sched.c:1024 > rpc_release_task net/sunrpc/sched.c:1068 [inline] > __rpc_execute+0x5e9/0xf50 net/sunrpc/sched.c:833 > rpc_execute+0x37f/0x480 net/sunrpc/sched.c:852 > rpc_run_task+0x615/0x8c0 net/sunrpc/clnt.c:1053 > rpc_call_sync+0x196/0x290 net/sunrpc/clnt.c:1082 > rpc_ping+0x155/0x1f0 net/sunrpc/clnt.c:2513 > rpc_create_xprt+0x282/0x3f0 net/sunrpc/clnt.c:479 > rpc_create+0x52e/0x900 net/sunrpc/clnt.c:587 > nfs_create_rpc_client+0x63e/0x850 fs/nfs/client.c:523 > nfs_init_client+0x74/0x100 fs/nfs/client.c:634 > nfs_get_client+0x1065/0x1500 fs/nfs/client.c:425 > nfs_init_server+0x364/0xfb0 fs/nfs/client.c:670 > nfs_create_server+0x86/0x5f0 fs/nfs/client.c:953 > nfs_try_mount+0x177/0xab0 fs/nfs/super.c:1884 > nfs_fs_mount+0x17de/0x2efd fs/nfs/super.c:2695 > mount_fs+0xae/0x328 fs/super.c:1267 > vfs_kern_mount.part.34+0xd4/0x4d0 fs/namespace.c:1037 > vfs_kern_mount fs/namespace.c:1027 [inline] > do_new_mount fs/namespace.c:2518 [inline] > do_mount+0x564/0x3070 fs/namespace.c:2848 > ksys_mount+0x12d/0x140 fs/namespace.c:3064 > __do_sys_mount fs/namespace.c:3078 [inline] > __se_sys_mount fs/namespace.c:3075 [inline] > __x64_sys_mount+0xbe/0x150 fs/namespace.c:3075 > do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > RIP: 0033:0x455979 > RSP: 002b:00007f1e2785bc68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 > RAX: ffffffffffffffda RBX: 00007f1e2785c6d4 RCX: 0000000000455979 > RDX: 0000000020fb5ffc RSI: 0000000020343ff8 RDI: 000000002091dff8 > RBP: 000000000072bf50 R08: 000000002000a000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff > R13: 0000000000000440 R14: 00000000006fa6a0 R15: 0000000000000001 > > Allocated by task 5079: > save_stack+0x43/0xd0 mm/kasan/kasan.c:448 > set_track mm/kasan/kasan.c:460 [inline] > kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553 > __do_kmalloc mm/slab.c:3718 [inline] > __kmalloc_track_caller+0x14a/0x760 mm/slab.c:3733 > kstrdup+0x39/0x70 mm/util.c:56 > xs_format_common_peer_ports+0x130/0x370 net/sunrpc/xprtsock.c:290 > xs_format_peer_addresses net/sunrpc/xprtsock.c:303 [inline] > xs_setup_udp+0x5ea/0x880 net/sunrpc/xprtsock.c:3037 > xprt_create_transport+0x1d7/0x596 net/sunrpc/xprt.c:1433 > rpc_create+0x489/0x900 net/sunrpc/clnt.c:573 > nfs_create_rpc_client+0x63e/0x850 fs/nfs/client.c:523 > nfs_init_client+0x74/0x100 fs/nfs/client.c:634 > nfs_get_client+0x1065/0x1500 fs/nfs/client.c:425 > nfs_init_server+0x364/0xfb0 fs/nfs/client.c:670 > nfs_create_server+0x86/0x5f0 fs/nfs/client.c:953 > nfs_try_mount+0x177/0xab0 fs/nfs/super.c:1884 > nfs_fs_mount+0x17de/0x2efd fs/nfs/super.c:2695 > mount_fs+0xae/0x328 fs/super.c:1267 > vfs_kern_mount.part.34+0xd4/0x4d0 fs/namespace.c:1037 > vfs_kern_mount fs/namespace.c:1027 [inline] > do_new_mount fs/namespace.c:2518 [inline] > do_mount+0x564/0x3070 fs/namespace.c:2848 > ksys_mount+0x12d/0x140 fs/namespace.c:3064 > __do_sys_mount fs/namespace.c:3078 [inline] > __se_sys_mount fs/namespace.c:3075 [inline] > __x64_sys_mount+0xbe/0x150 fs/namespace.c:3075 > do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > Freed by task 6: > save_stack+0x43/0xd0 mm/kasan/kasan.c:448 > set_track mm/kasan/kasan.c:460 [inline] > __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521 > kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 > __cache_free mm/slab.c:3498 [inline] > kfree+0xd9/0x260 mm/slab.c:3813 > xs_update_peer_port net/sunrpc/xprtsock.c:309 [inline] > xs_set_port+0x105/0x180 net/sunrpc/xprtsock.c:1827 > rpcb_getport_done+0x224/0x2d0 net/sunrpc/rpcb_clnt.c:824 > rpc_exit_task+0xc9/0x2d0 net/sunrpc/sched.c:725 > __rpc_execute+0x28a/0xf50 net/sunrpc/sched.c:784 > rpc_async_schedule+0x16/0x20 net/sunrpc/sched.c:857 > process_one_work+0xc1e/0x1b50 kernel/workqueue.c:2145 > worker_thread+0x1cc/0x1440 kernel/workqueue.c:2279 > kthread+0x345/0x410 kernel/kthread.c:238 > ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412 > > The buggy address belongs to the object at ffff8801d6f0a1c0 > which belongs to the cache kmalloc-32 of size 32 > The buggy address is located 0 bytes inside of > 32-byte region [ffff8801d6f0a1c0, ffff8801d6f0a1e0) > The buggy address belongs to the page: > page:ffffea00075bc280 count:1 mapcount:0 mapping:ffff8801d6f0a000 index:0xffff8801d6f0afc1 > flags: 0x2fffc0000000100(slab) > raw: 02fffc0000000100 ffff8801d6f0a000 ffff8801d6f0afc1 0000000100000024 > raw: ffffea00075c52a0 ffff8801da801238 ffff8801da8001c0 0000000000000000 > page dumped because: kasan: bad access detected > > Memory state around the buggy address: > ffff8801d6f0a080: 01 fc fc fc fc fc fc fc 00 02 fc fc fc fc fc fc > ffff8801d6f0a100: 00 02 fc fc fc fc fc fc 00 02 fc fc fc fc fc fc >> ffff8801d6f0a180: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc > ^ > ffff8801d6f0a200: 00 02 fc fc fc fc fc fc 01 fc fc fc fc fc fc fc > ffff8801d6f0a280: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc > ================================================================== The rpc_task survived longer than the transport. task->tk_xprt points to freed memory by the time rpc_count_iostats_metrics runs. The naive fix is to remove the references to task->tk_xprt in the trace point. I'm still checking to see if this is the fully correct fix. > --- > This bug is generated by a dumb bot. It may contain errors. > See https://goo.gl/tpsmEJ for details. > Direct all questions to syzkaller@xxxxxxxxxxxxxxxx. > > syzbot will keep track of this bug report. > If you forgot to add the Reported-by tag, once the fix for this bug is merged > into any tree, please reply to this email with: > #syz fix: exact-commit-title > To mark this as a duplicate of another syzbot report, please reply with: > #syz dup: exact-subject-of-another-report > If it's a one-off invalid bug report, please reply with: > #syz invalid > Note: if the crash happens again, it will cause creation of a new bug report. > Note: all commands must start from beginning of the line in the email body. > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Chuck Lever -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
