[ OK ] Reached target Graphical Interface. Starting Update UTMP about System Runlevel Changes... [ OK ] Started Update UTMP about System Runlevel Changes. Starting Load/Save RF Kill Switch Status... [ OK ] Started Load/Save RF Kill Switch Status. Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.0.80' (ECDSA) to the list of known hosts. executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program syzkaller login: [ 35.246509] ================================================================== [ 35.253986] BUG: KASAN: use-after-free in refcount_dec_not_one+0x71/0x1d0 [ 35.260912] Read of size 4 at addr ffff8880a8517d98 by task syz-executor373/8258 [ 35.268519] [ 35.270142] CPU: 0 PID: 8258 Comm: syz-executor373 Not tainted 4.19.211-syzkaller #0 [ 35.278119] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 35.287456] Call Trace: [ 35.290031] dump_stack+0x1fc/0x2ef [ 35.293655] print_address_description.cold+0x54/0x219 [ 35.298948] kasan_report_error.cold+0x8a/0x1b9 [ 35.303609] ? refcount_dec_not_one+0x71/0x1d0 [ 35.308202] kasan_report+0x8f/0xa0 [ 35.312033] ? refcount_dec_not_one+0x71/0x1d0 [ 35.316608] refcount_dec_not_one+0x71/0x1d0 [ 35.320999] ? refcount_dec_and_test_checked+0x20/0x20 [ 35.326278] ? nbd_config_put+0x5da/0x870 [ 35.330422] refcount_dec_and_mutex_lock+0x1c/0x80 [ 35.335359] nbd_genl_connect+0x11ee/0x1630 [ 35.339796] ? nbd_xmit_timeout+0x730/0x730 [ 35.344124] ? __sanitizer_cov_trace_switch+0x4b/0x80 [ 35.349404] ? validate_nla+0x270/0x820 [ 35.353371] ? nla_parse+0x1b2/0x290 [ 35.357073] genl_family_rcv_msg+0x642/0xc40 [ 35.361521] ? genl_rcv+0x40/0x40 [ 35.365051] ? genl_rcv_msg+0x12f/0x160 [ 35.369022] ? mutex_trylock+0x1a0/0x1a0 [ 35.373167] ? __radix_tree_lookup+0x216/0x370 [ 35.377779] genl_rcv_msg+0xbf/0x160 [ 35.381498] netlink_rcv_skb+0x160/0x440 [ 35.385552] ? genl_family_rcv_msg+0xc40/0xc40 [ 35.390130] ? netlink_ack+0xae0/0xae0 [ 35.394000] ? genl_rcv+0x15/0x40 [ 35.397449] genl_rcv+0x24/0x40 [ 35.400715] netlink_unicast+0x4d5/0x690 [ 35.404760] ? netlink_sendskb+0x110/0x110 [ 35.409065] ? _copy_from_iter_full+0x229/0x7c0 [ 35.413734] ? __phys_addr_symbol+0x2c/0x70 [ 35.418042] ? __check_object_size+0x17b/0x3e0 [ 35.422608] netlink_sendmsg+0x6c3/0xc50 [ 35.426700] ? aa_af_perm+0x230/0x230 [ 35.430489] ? nlmsg_notify+0x1f0/0x1f0 [ 35.434449] ? kernel_recvmsg+0x220/0x220 [ 35.438611] ? nlmsg_notify+0x1f0/0x1f0 [ 35.442660] sock_sendmsg+0xc3/0x120 [ 35.446360] ___sys_sendmsg+0x7bb/0x8e0 [ 35.450331] ? copy_msghdr_from_user+0x440/0x440 [ 35.455081] ? apparmor_file_receive+0x160/0x160 [ 35.459838] ? __lockdep_init_map+0x100/0x5a0 [ 35.464334] ? check_preemption_disabled+0x41/0x280 [ 35.469338] ? mark_held_locks+0xf0/0xf0 [ 35.473387] ? percpu_counter_add_batch+0x126/0x180 [ 35.478490] ? alloc_empty_file+0xd7/0x170 [ 35.482717] ? errseq_sample+0x56/0x70 [ 35.486599] ? alloc_file+0x326/0x4d0 [ 35.490396] ? __fd_install+0x1b4/0x610 [ 35.494551] ? __fdget+0x1a0/0x230 [ 35.498091] __x64_sys_sendmsg+0x132/0x220 [ 35.502306] ? __sys_sendmsg+0x1b0/0x1b0 [ 35.506358] ? entry_SYSCALL_64_after_hwframe+0x3e/0xbe [ 35.511720] ? trace_hardirqs_off_caller+0x6e/0x210 [ 35.516727] ? do_syscall_64+0x21/0x620 [ 35.520684] do_syscall_64+0xf9/0x620 [ 35.524469] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 35.529641] RIP: 0033:0x7fcf9ca41a69 [ 35.533336] Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 14 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 [ 35.552324] RSP: 002b:00007ffebbf18a38 EFLAGS: 00000246 ORIG_RAX: 000000000000002e [ 35.560018] RAX: ffffffffffffffda RBX: 00000000000f4240 RCX: 00007fcf9ca41a69 [ 35.567272] RDX: 0000000000000000 RSI: 00000000200006c0 RDI: 0000000000000004 [ 35.574528] RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000001 [ 35.581802] R10: 0000000000000000 R11: 0000000000000246 R12: 00000000000087af [ 35.589053] R13: 00007ffebbf18a4c R14: 00007ffebbf18a60 R15: 00007ffebbf18a50 [ 35.596308] [ 35.597918] Allocated by task 8245: [ 35.601529] kmem_cache_alloc_trace+0x12f/0x380 [ 35.606199] nbd_dev_add+0x44/0x890 [ 35.609831] nbd_genl_connect+0x4cc/0x1630 [ 35.614066] genl_family_rcv_msg+0x642/0xc40 [ 35.618471] genl_rcv_msg+0xbf/0x160 [ 35.622185] netlink_rcv_skb+0x160/0x440 [ 35.626228] genl_rcv+0x24/0x40 [ 35.629487] netlink_unicast+0x4d5/0x690 [ 35.633527] netlink_sendmsg+0x6c3/0xc50 [ 35.637579] sock_sendmsg+0xc3/0x120 [ 35.641282] ___sys_sendmsg+0x7bb/0x8e0 [ 35.645259] __x64_sys_sendmsg+0x132/0x220 [ 35.649483] do_syscall_64+0xf9/0x620 [ 35.653267] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 35.658436] [ 35.660062] Freed by task 8258: [ 35.663319] kfree+0xcc/0x210 [ 35.666411] nbd_put.part.0+0xfe/0x140 [ 35.670319] nbd_config_put+0x6a0/0x870 [ 35.674283] nbd_genl_connect+0x11bb/0x1630 [ 35.678593] genl_family_rcv_msg+0x642/0xc40 [ 35.682994] genl_rcv_msg+0xbf/0x160 [ 35.686693] netlink_rcv_skb+0x160/0x440 [ 35.690747] genl_rcv+0x24/0x40 [ 35.694166] netlink_unicast+0x4d5/0x690 [ 35.698225] netlink_sendmsg+0x6c3/0xc50 [ 35.702290] sock_sendmsg+0xc3/0x120 [ 35.706077] ___sys_sendmsg+0x7bb/0x8e0 [ 35.710034] __x64_sys_sendmsg+0x132/0x220 [ 35.714264] do_syscall_64+0xf9/0x620 [ 35.718061] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 35.723237] [ 35.724847] The buggy address belongs to the object at ffff8880a8517cc0 [ 35.724847] which belongs to the cache kmalloc-512 of size 512 [ 35.737582] The buggy address is located 216 bytes inside of [ 35.737582] 512-byte region [ffff8880a8517cc0, ffff8880a8517ec0) [ 35.749451] The buggy address belongs to the page: [ 35.754362] page:ffffea0002a145c0 count:1 mapcount:0 mapping:ffff88813bff0940 index:0x0 [ 35.762500] flags: 0xfff00000000100(slab) [ 35.766630] raw: 00fff00000000100 ffffea000286d688 ffffea000284db48 ffff88813bff0940 [ 35.774518] raw: 0000000000000000 ffff8880a8517040 0000000100000006 0000000000000000 [ 35.782420] page dumped because: kasan: bad access detected [ 35.788117] [ 35.789728] Memory state around the buggy address: [ 35.794649] ffff8880a8517c80: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb [ 35.802154] ffff8880a8517d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 35.809595] >ffff8880a8517d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 35.816936] ^ [ 35.821065] ffff8880a8517e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 35.828404] ffff8880a8517e80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc [ 35.835742] ================================================================== [ 35.843083] Disabling lock debugging due to kernel taint [ 35.854962] Kernel panic - not syncing: panic_on_warn set ... [ 35.854962] [ 35.862346] CPU: 1 PID: 8258 Comm: syz-executor373 Tainted: G B 4.19.211-syzkaller #0 [ 35.871637] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 35.880999] Call Trace: [ 35.883586] dump_stack+0x1fc/0x2ef [ 35.887205] panic+0x26a/0x50e [ 35.890377] ? __warn_printk+0xf3/0xf3 [ 35.894264] ? preempt_schedule_common+0x45/0xc0 [ 35.899013] ? ___preempt_schedule+0x16/0x18 [ 35.903399] ? trace_hardirqs_on+0x55/0x210 [ 35.907733] kasan_end_report+0x43/0x49 [ 35.911705] kasan_report_error.cold+0xa7/0x1b9 [ 35.916360] ? refcount_dec_not_one+0x71/0x1d0 [ 35.920935] kasan_report+0x8f/0xa0 [ 35.924551] ? refcount_dec_not_one+0x71/0x1d0 [ 35.929228] refcount_dec_not_one+0x71/0x1d0 [ 35.933628] ? refcount_dec_and_test_checked+0x20/0x20 [ 35.938888] ? nbd_config_put+0x5da/0x870 [ 35.943015] refcount_dec_and_mutex_lock+0x1c/0x80 [ 35.947937] nbd_genl_connect+0x11ee/0x1630 [ 35.952242] ? nbd_xmit_timeout+0x730/0x730 [ 35.956553] ? __sanitizer_cov_trace_switch+0x4b/0x80 [ 35.961751] ? validate_nla+0x270/0x820 [ 35.965707] ? nla_parse+0x1b2/0x290 [ 35.969400] genl_family_rcv_msg+0x642/0xc40 [ 35.973789] ? genl_rcv+0x40/0x40 [ 35.977224] ? genl_rcv_msg+0x12f/0x160 [ 35.981188] ? mutex_trylock+0x1a0/0x1a0 [ 35.985335] ? __radix_tree_lookup+0x216/0x370 [ 35.989984] genl_rcv_msg+0xbf/0x160 [ 35.993678] netlink_rcv_skb+0x160/0x440 [ 35.997719] ? genl_family_rcv_msg+0xc40/0xc40 [ 36.002279] ? netlink_ack+0xae0/0xae0 [ 36.006157] ? genl_rcv+0x15/0x40 [ 36.009598] genl_rcv+0x24/0x40 [ 36.012855] netlink_unicast+0x4d5/0x690 [ 36.016895] ? netlink_sendskb+0x110/0x110 [ 36.021196] ? _copy_from_iter_full+0x229/0x7c0 [ 36.026108] ? __phys_addr_symbol+0x2c/0x70 [ 36.030406] ? __check_object_size+0x17b/0x3e0 [ 36.035063] netlink_sendmsg+0x6c3/0xc50 [ 36.039104] ? aa_af_perm+0x230/0x230 [ 36.042882] ? nlmsg_notify+0x1f0/0x1f0 [ 36.046834] ? kernel_recvmsg+0x220/0x220 [ 36.050961] ? nlmsg_notify+0x1f0/0x1f0 [ 36.054914] sock_sendmsg+0xc3/0x120 [ 36.058604] ___sys_sendmsg+0x7bb/0x8e0 [ 36.062557] ? copy_msghdr_from_user+0x440/0x440 [ 36.067293] ? apparmor_file_receive+0x160/0x160 [ 36.072028] ? __lockdep_init_map+0x100/0x5a0 [ 36.076502] ? check_preemption_disabled+0x41/0x280 [ 36.081497] ? mark_held_locks+0xf0/0xf0 [ 36.085588] ? percpu_counter_add_batch+0x126/0x180 [ 36.090631] ? alloc_empty_file+0xd7/0x170 [ 36.094842] ? errseq_sample+0x56/0x70 [ 36.098810] ? alloc_file+0x326/0x4d0 [ 36.102602] ? __fd_install+0x1b4/0x610 [ 36.106655] ? __fdget+0x1a0/0x230 [ 36.110278] __x64_sys_sendmsg+0x132/0x220 [ 36.114508] ? __sys_sendmsg+0x1b0/0x1b0 [ 36.118572] ? entry_SYSCALL_64_after_hwframe+0x3e/0xbe [ 36.123930] ? trace_hardirqs_off_caller+0x6e/0x210 [ 36.128926] ? do_syscall_64+0x21/0x620 [ 36.132880] do_syscall_64+0xf9/0x620 [ 36.136661] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 36.142105] RIP: 0033:0x7fcf9ca41a69 [ 36.146012] Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 14 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 [ 36.164891] RSP: 002b:00007ffebbf18a38 EFLAGS: 00000246 ORIG_RAX: 000000000000002e [ 36.172578] RAX: ffffffffffffffda RBX: 00000000000f4240 RCX: 00007fcf9ca41a69 [ 36.179824] RDX: 0000000000000000 RSI: 00000000200006c0 RDI: 0000000000000004 [ 36.187072] RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000001 [ 36.194333] R10: 0000000000000000 R11: 0000000000000246 R12: 00000000000087af [ 36.201613] R13: 00007ffebbf18a4c R14: 00007ffebbf18a60 R15: 00007ffebbf18a50 [ 36.209057] Kernel Offset: disabled [ 36.212693] Rebooting in 86400 seconds..