[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. Starting mcstransd: [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting file context maintaining daemon: restorecond[?25l[?1c7[ ok 8[?25h[?0c. [ 36.513610] audit: type=1800 audit(1569143192.022:33): pid=7275 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 [ 36.535027] audit: type=1800 audit(1569143192.022:34): pid=7275 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 Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 42.276571] audit: type=1400 audit(1569143197.782:35): avc: denied { map } for pid=7450 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 '10.128.0.7' (ECDSA) to the list of known hosts. executing program [ 48.667239] audit: type=1400 audit(1569143204.172:36): avc: denied { map } for pid=7462 comm="syz-executor601" path="/root/syz-executor601847340" 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 [ 48.691233] ================================================================== [ 48.700888] BUG: KASAN: use-after-free in wait_consider_task+0x1b51/0x3910 [ 48.707885] Read of size 4 at addr ffff8880a79ceb6c by task syz-executor601/7462 [ 48.715397] [ 48.717007] CPU: 1 PID: 7462 Comm: syz-executor601 Not tainted 4.19.75 #0 [ 48.723909] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 48.733239] Call Trace: [ 48.735804] dump_stack+0x172/0x1f0 [ 48.739412] ? wait_consider_task+0x1b51/0x3910 [ 48.744104] print_address_description.cold+0x7c/0x20d [ 48.749371] ? wait_consider_task+0x1b51/0x3910 [ 48.754017] kasan_report.cold+0x8c/0x2ba [ 48.758145] __asan_report_load4_noabort+0x14/0x20 [ 48.763055] wait_consider_task+0x1b51/0x3910 [ 48.767530] ? lockdep_hardirqs_on+0x415/0x5d0 [ 48.772095] ? _raw_spin_unlock_irqrestore+0x6b/0xe0 [ 48.777175] ? add_wait_queue+0x112/0x170 [ 48.781472] ? release_task+0x1630/0x1630 [ 48.785597] ? lock_acquire+0x16f/0x3f0 [ 48.789551] ? do_wait+0x3aa/0x9d0 [ 48.793078] ? kasan_check_write+0x14/0x20 [ 48.797303] do_wait+0x439/0x9d0 [ 48.800656] ? wait_consider_task+0x3910/0x3910 [ 48.805412] kernel_wait4+0x171/0x290 [ 48.809285] ? __ia32_sys_waitid+0x140/0x140 [ 48.813676] ? task_stopped_code+0x180/0x180 [ 48.818067] __do_sys_wait4+0x147/0x160 [ 48.822041] ? kernel_wait4+0x290/0x290 [ 48.826001] ? _copy_to_user+0xc9/0x120 [ 48.829976] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 48.835494] ? put_timespec64+0xda/0x140 [ 48.839543] ? nsecs_to_jiffies+0x30/0x30 [ 48.843727] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 48.848464] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 48.853199] ? do_syscall_64+0x26/0x620 [ 48.857153] ? entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 48.862494] ? do_syscall_64+0x26/0x620 [ 48.866458] __x64_sys_wait4+0x97/0xf0 [ 48.870339] do_syscall_64+0xfd/0x620 [ 48.874121] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 48.879292] RIP: 0033:0x40110a [ 48.882464] Code: c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 8b 05 ce 15 2d 00 85 c0 75 36 45 31 d2 48 63 d2 48 63 ff b8 3d 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 06 c3 0f 1f 44 00 00 48 c7 c2 d0 ff ff ff f7 [ 48.901347] RSP: 002b:00007fffaf8241b8 EFLAGS: 00000246 ORIG_RAX: 000000000000003d [ 48.909048] RAX: ffffffffffffffda RBX: 0000000000001d27 RCX: 000000000040110a [ 48.916300] RDX: 0000000040000001 RSI: 00007fffaf8241c4 RDI: ffffffffffffffff [ 48.923556] RBP: 000000000000be02 R08: 0000000000000000 R09: 000055555580e880 [ 48.930827] R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004020c0 [ 48.938079] R13: 0000000000402150 R14: 0000000000000000 R15: 0000000000000000 [ 48.945464] [ 48.947071] Allocated by task 7462: [ 48.950684] save_stack+0x45/0xd0 [ 48.954120] kasan_kmalloc+0xce/0xf0 [ 48.957815] kasan_slab_alloc+0xf/0x20 [ 48.961684] kmem_cache_alloc_node+0x144/0x710 [ 48.966252] copy_process.part.0+0x1ce0/0x7a30 [ 48.970824] _do_fork+0x257/0xfd0 [ 48.974261] __x64_sys_clone+0xbf/0x150 [ 48.978218] do_syscall_64+0xfd/0x620 [ 48.982000] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 48.987164] [ 48.988771] Freed by task 0: [ 48.991810] save_stack+0x45/0xd0 [ 48.995240] __kasan_slab_free+0x102/0x150 [ 48.999454] kasan_slab_free+0xe/0x10 [ 49.003233] kmem_cache_free+0x86/0x260 [ 49.007183] free_task+0xdd/0x120 [ 49.010611] __put_task_struct+0x20f/0x4c0 [ 49.014821] finish_task_switch+0x52b/0x780 [ 49.019122] __schedule+0x86e/0x1dc0 [ 49.022814] schedule_idle+0x58/0x80 [ 49.026504] do_idle+0x192/0x560 [ 49.029847] cpu_startup_entry+0xc8/0xe0 [ 49.033895] start_secondary+0x3e8/0x5b0 [ 49.037933] secondary_startup_64+0xa4/0xb0 [ 49.042245] [ 49.043851] The buggy address belongs to the object at ffff8880a79ce700 [ 49.043851] which belongs to the cache task_struct of size 6080 [ 49.056582] The buggy address is located 1132 bytes inside of [ 49.056582] 6080-byte region [ffff8880a79ce700, ffff8880a79cfec0) [ 49.068610] The buggy address belongs to the page: [ 49.073530] page:ffffea00029e7380 count:1 mapcount:0 mapping:ffff88812c26d800 index:0x0 compound_mapcount: 0 [ 49.083486] flags: 0x1fffc0000008100(slab|head) [ 49.088149] raw: 01fffc0000008100 ffffea00025e4388 ffffea0002800388 ffff88812c26d800 [ 49.096008] raw: 0000000000000000 ffff8880a79ce700 0000000100000001 0000000000000000 [ 49.103872] page dumped because: kasan: bad access detected [ 49.109555] [ 49.111169] Memory state around the buggy address: [ 49.116078] ffff8880a79cea00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 49.123412] ffff8880a79cea80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 49.130747] >ffff8880a79ceb00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 49.138082] ^ [ 49.144814] ffff8880a79ceb80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 49.152149] ffff8880a79cec00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 49.159484] ================================================================== [ 49.166818] Disabling lock debugging due to kernel taint [ 49.172564] Kernel panic - not syncing: panic_on_warn set ... [ 49.172564] [ 49.179936] CPU: 1 PID: 7462 Comm: syz-executor601 Tainted: G B 4.19.75 #0 [ 49.188234] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 49.197573] Call Trace: [ 49.200140] dump_stack+0x172/0x1f0 [ 49.203747] ? wait_consider_task+0x1b51/0x3910 [ 49.208392] panic+0x263/0x507 [ 49.211564] ? __warn_printk+0xf3/0xf3 [ 49.215431] ? retint_kernel+0x2d/0x2d [ 49.219300] ? trace_hardirqs_on+0x5e/0x220 [ 49.223600] ? wait_consider_task+0x1b51/0x3910 [ 49.228248] kasan_end_report+0x47/0x4f [ 49.232203] kasan_report.cold+0xa9/0x2ba [ 49.236331] __asan_report_load4_noabort+0x14/0x20 [ 49.241239] wait_consider_task+0x1b51/0x3910 [ 49.245717] ? lockdep_hardirqs_on+0x415/0x5d0 [ 49.250279] ? _raw_spin_unlock_irqrestore+0x6b/0xe0 [ 49.255360] ? add_wait_queue+0x112/0x170 [ 49.259485] ? release_task+0x1630/0x1630 [ 49.263626] ? lock_acquire+0x16f/0x3f0 [ 49.267604] ? do_wait+0x3aa/0x9d0 [ 49.271129] ? kasan_check_write+0x14/0x20 [ 49.275340] do_wait+0x439/0x9d0 [ 49.278687] ? wait_consider_task+0x3910/0x3910 [ 49.283336] kernel_wait4+0x171/0x290 [ 49.287113] ? __ia32_sys_waitid+0x140/0x140 [ 49.291504] ? task_stopped_code+0x180/0x180 [ 49.295894] __do_sys_wait4+0x147/0x160 [ 49.299847] ? kernel_wait4+0x290/0x290 [ 49.303803] ? _copy_to_user+0xc9/0x120 [ 49.307759] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 49.313276] ? put_timespec64+0xda/0x140 [ 49.317314] ? nsecs_to_jiffies+0x30/0x30 [ 49.321444] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 49.326177] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 49.330909] ? do_syscall_64+0x26/0x620 [ 49.334866] ? entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 49.340205] ? do_syscall_64+0x26/0x620 [ 49.344157] __x64_sys_wait4+0x97/0xf0 [ 49.348033] do_syscall_64+0xfd/0x620 [ 49.351830] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 49.356996] RIP: 0033:0x40110a [ 49.360188] Code: c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 8b 05 ce 15 2d 00 85 c0 75 36 45 31 d2 48 63 d2 48 63 ff b8 3d 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 06 c3 0f 1f 44 00 00 48 c7 c2 d0 ff ff ff f7 [ 49.379065] RSP: 002b:00007fffaf8241b8 EFLAGS: 00000246 ORIG_RAX: 000000000000003d [ 49.386747] RAX: ffffffffffffffda RBX: 0000000000001d27 RCX: 000000000040110a [ 49.394001] RDX: 0000000040000001 RSI: 00007fffaf8241c4 RDI: ffffffffffffffff [ 49.401252] RBP: 000000000000be02 R08: 0000000000000000 R09: 000055555580e880 [ 49.408508] R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004020c0 [ 49.415766] R13: 0000000000402150 R14: 0000000000000000 R15: 0000000000000000 [ 49.424177] Kernel Offset: disabled [ 49.427792] Rebooting in 86400 seconds..