[....] Starting periodic command[ 35.729260] audit: type=1800 audit(1569068057.228:32): pid=7293 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:kernel_t:s0 op=collect_data cause=failed(directio) comm="startpar" name="ssh" dev="sda1" ino=2450 res=0 scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0[ 36.391897] audit: type=1800 audit(1569068057.888:33): pid=7293 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:kernel_t:s0 op=collect_data cause=failed(directio) comm="startpar" name="rc.local" dev="sda1" ino=2465 res=0 c. [....] Starting file context maintaining daemon: restorecond[?25l[?1c7[ ok [39;[ 36.420386] audit: type=1800 audit(1569068057.888:34): pid=7293 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:kernel_t:s0 op=collect_data cause=failed(directio) comm="startpar" name="rmnologin" dev="sda1" ino=2456 res=0 49m8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 43.908614] audit: type=1400 audit(1569068065.408:35): avc: denied { map } for pid=7466 comm="bash" path="/bin/bash" dev="sda1" ino=1457 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1 Warning: Permanently added '10.128.0.52' (ECDSA) to the list of known hosts. executing program [ 50.477534] audit: type=1400 audit(1569068071.978:36): avc: denied { map } for pid=7478 comm="syz-executor181" path="/root/syz-executor181873823" dev="sda1" ino=16483 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1 [ 50.510352] ================================================================== [ 50.517893] BUG: KASAN: use-after-free in wait_consider_task+0x1b51/0x3910 [ 50.524899] Read of size 4 at addr ffff888086a16b6c by task sshd/7476 [ 50.531463] [ 50.533128] CPU: 1 PID: 7476 Comm: sshd Not tainted 4.19.75 #0 [ 50.539080] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 50.548470] Call Trace: [ 50.551097] dump_stack+0x172/0x1f0 [ 50.554797] ? wait_consider_task+0x1b51/0x3910 [ 50.559465] print_address_description.cold+0x7c/0x20d [ 50.564806] ? wait_consider_task+0x1b51/0x3910 [ 50.569482] kasan_report.cold+0x8c/0x2ba [ 50.573619] __asan_report_load4_noabort+0x14/0x20 [ 50.578535] wait_consider_task+0x1b51/0x3910 [ 50.583020] ? _raw_spin_unlock_irqrestore+0x6b/0xe0 [ 50.588108] ? add_wait_queue+0x112/0x170 [ 50.592244] ? release_task+0x1630/0x1630 [ 50.596387] ? lock_acquire+0x16f/0x3f0 [ 50.600361] ? do_wait+0x3aa/0x9d0 [ 50.603886] ? kasan_check_write+0x14/0x20 [ 50.608133] do_wait+0x439/0x9d0 [ 50.611491] ? wait_consider_task+0x3910/0x3910 [ 50.616166] ? mark_held_locks+0x100/0x100 [ 50.620389] kernel_wait4+0x171/0x290 [ 50.624174] ? __ia32_sys_waitid+0x140/0x140 [ 50.628584] ? task_stopped_code+0x180/0x180 [ 50.632989] __do_sys_wait4+0x147/0x160 [ 50.636951] ? kernel_wait4+0x290/0x290 [ 50.640917] ? kasan_check_read+0x11/0x20 [ 50.645049] ? _copy_to_user+0xc9/0x120 [ 50.649014] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 50.654561] ? __x64_sys_rt_sigprocmask+0x21d/0x2e0 [ 50.659568] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 50.664306] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 50.669060] ? do_syscall_64+0x26/0x620 [ 50.673020] ? entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 50.678367] ? do_syscall_64+0x26/0x620 [ 50.682328] __x64_sys_wait4+0x97/0xf0 [ 50.686355] do_syscall_64+0xfd/0x620 [ 50.690162] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 50.695344] RIP: 0033:0x7f7d05ad9a3e [ 50.699063] Code: 90 90 90 90 90 90 90 90 90 90 90 90 48 83 ec 28 8b 05 c2 eb 2d 00 85 c0 75 1d 45 31 d2 48 63 d2 48 63 ff b8 3d 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 55 48 83 c4 28 c3 89 54 24 08 48 89 74 24 10 [ 50.717951] RSP: 002b:00007ffd783a6390 EFLAGS: 00000246 ORIG_RAX: 000000000000003d [ 50.725645] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f7d05ad9a3e [ 50.732902] RDX: 0000000000000001 RSI: 00007ffd783a63cc RDI: ffffffffffffffff [ 50.740167] RBP: 00005561aca2cc88 R08: 00007ffd783a6490 R09: 0101010101010101 [ 50.747434] R10: 0000000000000000 R11: 0000000000000246 R12: 00005561aced5c00 [ 50.754721] R13: 00005561aca2afb4 R14: 0000000000000028 R15: 00005561aca2cca0 [ 50.761993] [ 50.763617] Allocated by task 7476: [ 50.767329] save_stack+0x45/0xd0 [ 50.770765] kasan_kmalloc+0xce/0xf0 [ 50.774487] kasan_slab_alloc+0xf/0x20 [ 50.778381] kmem_cache_alloc_node+0x144/0x710 [ 50.782966] copy_process.part.0+0x1ce0/0x7a30 [ 50.787536] _do_fork+0x257/0xfd0 [ 50.790986] __x64_sys_clone+0xbf/0x150 [ 50.794951] do_syscall_64+0xfd/0x620 [ 50.798738] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 50.803907] [ 50.805545] Freed by task 0: [ 50.808550] save_stack+0x45/0xd0 [ 50.812084] __kasan_slab_free+0x102/0x150 [ 50.816302] kasan_slab_free+0xe/0x10 [ 50.820085] kmem_cache_free+0x86/0x260 [ 50.824042] free_task+0xdd/0x120 [ 50.827479] __put_task_struct+0x20f/0x4c0 [ 50.831708] finish_task_switch+0x52b/0x780 [ 50.836121] __schedule+0x86e/0x1dc0 [ 50.839821] schedule_idle+0x58/0x80 [ 50.843515] do_idle+0x192/0x560 [ 50.846865] cpu_startup_entry+0xc8/0xe0 [ 50.850906] rest_init+0x219/0x222 [ 50.854433] start_kernel+0x88c/0x8c5 [ 50.858237] x86_64_start_reservations+0x29/0x2b [ 50.863078] x86_64_start_kernel+0x77/0x7b [ 50.867314] secondary_startup_64+0xa4/0xb0 [ 50.871622] [ 50.873241] The buggy address belongs to the object at ffff888086a16700 [ 50.873241] which belongs to the cache task_struct of size 6080 [ 50.885986] The buggy address is located 1132 bytes inside of [ 50.885986] 6080-byte region [ffff888086a16700, ffff888086a17ec0) [ 50.898019] The buggy address belongs to the page: [ 50.902949] page:ffffea00021a8580 count:1 mapcount:0 mapping:ffff88812c26d800 index:0x0 compound_mapcount: 0 [ 50.912906] flags: 0x1fffc0000008100(slab|head) [ 50.917573] raw: 01fffc0000008100 ffffea00021a8388 ffffea0002840588 ffff88812c26d800 [ 50.925451] raw: 0000000000000000 ffff888086a16700 0000000100000001 0000000000000000 [ 50.933350] page dumped because: kasan: bad access detected [ 50.939050] [ 50.940822] Memory state around the buggy address: [ 50.945744] ffff888086a16a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 50.953096] ffff888086a16a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 50.960453] >ffff888086a16b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 50.967807] ^ [ 50.974540] ffff888086a16b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 50.984140] ffff888086a16c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 50.991493] ================================================================== [ 50.998846] Disabling lock debugging due to kernel taint [ 51.004387] Kernel panic - not syncing: panic_on_warn set ... [ 51.004387] [ 51.011764] CPU: 1 PID: 7476 Comm: sshd Tainted: G B 4.19.75 #0 [ 51.019107] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 51.028453] Call Trace: [ 51.031028] dump_stack+0x172/0x1f0 [ 51.034653] ? wait_consider_task+0x1b51/0x3910 [ 51.039306] panic+0x263/0x507 [ 51.042482] ? __warn_printk+0xf3/0xf3 [ 51.046354] ? retint_kernel+0x2d/0x2d [ 51.050235] ? trace_hardirqs_on+0x5e/0x220 [ 51.054554] ? wait_consider_task+0x1b51/0x3910 [ 51.059210] kasan_end_report+0x47/0x4f [ 51.063181] kasan_report.cold+0xa9/0x2ba [ 51.067312] __asan_report_load4_noabort+0x14/0x20 [ 51.072226] wait_consider_task+0x1b51/0x3910 [ 51.076708] ? _raw_spin_unlock_irqrestore+0x6b/0xe0 [ 51.081806] ? add_wait_queue+0x112/0x170 [ 51.085944] ? release_task+0x1630/0x1630 [ 51.090079] ? lock_acquire+0x16f/0x3f0 [ 51.094109] ? do_wait+0x3aa/0x9d0 [ 51.097751] ? kasan_check_write+0x14/0x20 [ 51.101976] do_wait+0x439/0x9d0 [ 51.105346] ? wait_consider_task+0x3910/0x3910 [ 51.110013] ? mark_held_locks+0x100/0x100 [ 51.114236] kernel_wait4+0x171/0x290 [ 51.118024] ? __ia32_sys_waitid+0x140/0x140 [ 51.122450] ? task_stopped_code+0x180/0x180 [ 51.126866] __do_sys_wait4+0x147/0x160 [ 51.130828] ? kernel_wait4+0x290/0x290 [ 51.134819] ? kasan_check_read+0x11/0x20 [ 51.138963] ? _copy_to_user+0xc9/0x120 [ 51.142926] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 51.148453] ? __x64_sys_rt_sigprocmask+0x21d/0x2e0 [ 51.153452] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 51.158202] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 51.162951] ? do_syscall_64+0x26/0x620 [ 51.166915] ? entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 51.172261] ? do_syscall_64+0x26/0x620 [ 51.176231] __x64_sys_wait4+0x97/0xf0 [ 51.180102] do_syscall_64+0xfd/0x620 [ 51.183899] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 51.189071] RIP: 0033:0x7f7d05ad9a3e [ 51.192785] Code: 90 90 90 90 90 90 90 90 90 90 90 90 48 83 ec 28 8b 05 c2 eb 2d 00 85 c0 75 1d 45 31 d2 48 63 d2 48 63 ff b8 3d 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 55 48 83 c4 28 c3 89 54 24 08 48 89 74 24 10 [ 51.211685] RSP: 002b:00007ffd783a6390 EFLAGS: 00000246 ORIG_RAX: 000000000000003d [ 51.219377] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f7d05ad9a3e [ 51.226630] RDX: 0000000000000001 RSI: 00007ffd783a63cc RDI: ffffffffffffffff [ 51.233893] RBP: 00005561aca2cc88 R08: 00007ffd783a6490 R09: 0101010101010101 [ 51.241269] R10: 0000000000000000 R11: 0000000000000246 R12: 00005561aced5c00 [ 51.248531] R13: 00005561aca2afb4 R14: 0000000000000028 R15: 00005561aca2cca0 [ 51.257204] Kernel Offset: disabled [ 51.260832] Rebooting in 86400 seconds..