[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 59.340664][ T23] audit: type=1800 audit(1575417749.623:25): pid=8772 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 59.375352][ T23] audit: type=1800 audit(1575417749.623:26): pid=8772 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 59.412854][ T23] audit: type=1800 audit(1575417749.623:27): pid=8772 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="restorecond" dev="sda1" ino=2436 res=0 [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 Warning: Permanently added '10.128.0.175' (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 syzkaller login: [ 90.182351][ T8951] ================================================================== [ 90.182393][ T8951] BUG: KASAN: use-after-free in tty_open+0x6f8/0xbb0 [ 90.182402][ T8951] Read of size 8 at addr ffff8880a7e49200 by task syz-executor641/8951 [ 90.182405][ T8951] [ 90.182418][ T8951] CPU: 0 PID: 8951 Comm: syz-executor641 Not tainted 5.4.0-syzkaller #0 [ 90.182424][ T8951] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 90.182427][ T8951] Call Trace: [ 90.182443][ T8951] dump_stack+0x197/0x210 [ 90.182458][ T8951] ? tty_open+0x6f8/0xbb0 [ 90.182474][ T8951] print_address_description.constprop.0.cold+0xd4/0x30b [ 90.182483][ T8951] ? tty_open+0x6f8/0xbb0 [ 90.182491][ T8951] ? tty_open+0x6f8/0xbb0 [ 90.182502][ T8951] __kasan_report.cold+0x1b/0x41 [ 90.182513][ T8951] ? tty_open+0x6f8/0xbb0 [ 90.182524][ T8951] kasan_report+0x12/0x20 [ 90.182535][ T8951] check_memory_region+0x134/0x1a0 [ 90.182546][ T8951] __kasan_check_read+0x11/0x20 [ 90.182554][ T8951] tty_open+0x6f8/0xbb0 [ 90.182568][ T8951] ? tty_init_dev+0x460/0x460 [ 90.182584][ T8951] ? do_raw_spin_unlock+0x178/0x270 [ 90.182595][ T8951] ? tty_init_dev+0x460/0x460 [ 90.182607][ T8951] chrdev_open+0x245/0x6b0 [ 90.182620][ T8951] ? cdev_put.part.0+0x50/0x50 [ 90.182636][ T8951] ? security_file_open+0x87/0x300 [ 90.182650][ T8951] do_dentry_open+0x4e6/0x1380 [ 90.182659][ T8951] ? __kasan_check_read+0x11/0x20 [ 90.182670][ T8951] ? cdev_put.part.0+0x50/0x50 [ 90.182684][ T8951] ? chown_common+0x5c0/0x5c0 [ 90.182697][ T8951] ? inode_permission+0xb4/0x520 [ 90.182710][ T8951] vfs_open+0xa0/0xd0 [ 90.182721][ T8951] path_openat+0x10e4/0x4710 [ 90.182731][ T8951] ? __kasan_kmalloc.constprop.0+0xcf/0xe0 [ 90.182739][ T8951] ? kasan_slab_alloc+0xf/0x20 [ 90.182751][ T8951] ? kmem_cache_alloc+0x121/0x710 [ 90.182760][ T8951] ? getname_flags+0xd6/0x5b0 [ 90.182774][ T8951] ? getname+0x1a/0x20 [ 90.182783][ T8951] ? do_sys_open+0x2c9/0x5d0 [ 90.182803][ T8951] ? path_lookupat.isra.0+0x8d0/0x8d0 [ 90.182818][ T8951] ? __alloc_fd+0x487/0x620 [ 90.182833][ T8951] do_filp_open+0x1a1/0x280 [ 90.182845][ T8951] ? may_open_dev+0x100/0x100 [ 90.182863][ T8951] ? do_raw_spin_unlock+0x178/0x270 [ 90.182876][ T8951] ? _raw_spin_unlock+0x28/0x40 [ 90.182886][ T8951] ? __alloc_fd+0x487/0x620 [ 90.182904][ T8951] do_sys_open+0x3fe/0x5d0 [ 90.182916][ T8951] ? filp_open+0x80/0x80 [ 90.182930][ T8951] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 90.182942][ T8951] ? do_fast_syscall_32+0xd1/0xe16 [ 90.182952][ T8951] ? entry_SYSENTER_compat+0x70/0x7f [ 90.182962][ T8951] ? do_fast_syscall_32+0xd1/0xe16 [ 90.182976][ T8951] __ia32_compat_sys_open+0x79/0xb0 [ 90.182988][ T8951] do_fast_syscall_32+0x27b/0xe16 [ 90.183003][ T8951] entry_SYSENTER_compat+0x70/0x7f [ 90.183012][ T8951] RIP: 0023:0xf7f89a39 [ 90.183023][ T8951] Code: 00 00 00 89 d3 5b 5e 5f 5d c3 b8 80 96 98 00 eb c4 8b 04 24 c3 8b 1c 24 c3 8b 34 24 c3 8b 3c 24 c3 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90 [ 90.183029][ T8951] RSP: 002b:00000000fff1d018 EFLAGS: 00000246 ORIG_RAX: 0000000000000005 [ 90.183039][ T8951] RAX: ffffffffffffffda RBX: 00000000fff1d05c RCX: 0000000000127200 [ 90.183045][ T8951] RDX: 0000000000000000 RSI: 00000000fff1d05c RDI: 0000000000000000 [ 90.183051][ T8951] RBP: 00000000fff1d4a8 R08: 0000000000000000 R09: 0000000000000000 [ 90.183057][ T8951] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 [ 90.183062][ T8951] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 [ 90.183076][ T8951] [ 90.183081][ T8951] Allocated by task 8949: [ 90.183090][ T8951] save_stack+0x23/0x90 [ 90.183099][ T8951] __kasan_kmalloc.constprop.0+0xcf/0xe0 [ 90.183106][ T8951] kasan_kmalloc+0x9/0x10 [ 90.183116][ T8951] kmem_cache_alloc_trace+0x158/0x790 [ 90.183125][ T8951] vc_allocate+0x1fc/0x760 [ 90.183132][ T8951] con_install+0x52/0x410 [ 90.183140][ T8951] tty_init_dev+0xf7/0x460 [ 90.183147][ T8951] tty_open+0x4a5/0xbb0 [ 90.183157][ T8951] chrdev_open+0x245/0x6b0 [ 90.183166][ T8951] do_dentry_open+0x4e6/0x1380 [ 90.183173][ T8951] vfs_open+0xa0/0xd0 [ 90.183182][ T8951] path_openat+0x10e4/0x4710 [ 90.183191][ T8951] do_filp_open+0x1a1/0x280 [ 90.183199][ T8951] do_sys_open+0x3fe/0x5d0 [ 90.183207][ T8951] __ia32_compat_sys_open+0x79/0xb0 [ 90.183216][ T8951] do_fast_syscall_32+0x27b/0xe16 [ 90.183226][ T8951] entry_SYSENTER_compat+0x70/0x7f [ 90.183229][ T8951] [ 90.183233][ T8951] Freed by task 8950: [ 90.183241][ T8951] save_stack+0x23/0x90 [ 90.183249][ T8951] __kasan_slab_free+0x102/0x150 [ 90.183257][ T8951] kasan_slab_free+0xe/0x10 [ 90.183266][ T8951] kfree+0x10a/0x2c0 [ 90.183276][ T8951] vt_disallocate_all+0x2bd/0x3e0 [ 90.183283][ T8951] vt_ioctl+0xc38/0x26d0 [ 90.183292][ T8951] vt_compat_ioctl+0x457/0x7a0 [ 90.183299][ T8951] tty_compat_ioctl+0x1b0/0x420 [ 90.183310][ T8951] __ia32_compat_sys_ioctl+0x233/0x610 [ 90.183320][ T8951] do_fast_syscall_32+0x27b/0xe16 [ 90.183330][ T8951] entry_SYSENTER_compat+0x70/0x7f [ 90.183332][ T8951] [ 90.183340][ T8951] The buggy address belongs to the object at ffff8880a7e49000 [ 90.183340][ T8951] which belongs to the cache kmalloc-2k of size 2048 [ 90.183349][ T8951] The buggy address is located 512 bytes inside of [ 90.183349][ T8951] 2048-byte region [ffff8880a7e49000, ffff8880a7e49800) [ 90.183352][ T8951] The buggy address belongs to the page: [ 90.183362][ T8951] page:ffffea00029f9240 refcount:1 mapcount:0 mapping:ffff8880aa400e00 index:0x0 [ 90.183376][ T8951] raw: 00fffe0000000200 ffffea0002526a88 ffffea00027eb148 ffff8880aa400e00 [ 90.183388][ T8951] raw: 0000000000000000 ffff8880a7e49000 0000000100000001 0000000000000000 [ 90.183393][ T8951] page dumped because: kasan: bad access detected [ 90.183395][ T8951] [ 90.183399][ T8951] Memory state around the buggy address: [ 90.183412][ T8951] ffff8880a7e49100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 90.183420][ T8951] ffff8880a7e49180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 90.183428][ T8951] >ffff8880a7e49200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 90.183431][ T8951] ^ [ 90.183439][ T8951] ffff8880a7e49280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 90.183446][ T8951] ffff8880a7e49300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 90.183450][ T8951] ================================================================== [ 90.183454][ T8951] Disabling lock debugging due to kernel taint [ 90.183597][ T8951] Kernel panic - not syncing: panic_on_warn set ... [ 90.810490][ T8951] CPU: 0 PID: 8951 Comm: syz-executor641 Tainted: G B 5.4.0-syzkaller #0 [ 90.820181][ T8951] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 90.830389][ T8951] Call Trace: [ 90.833674][ T8951] dump_stack+0x197/0x210 [ 90.838002][ T8951] panic+0x2e3/0x75c [ 90.841879][ T8951] ? add_taint.cold+0x16/0x16 [ 90.846537][ T8951] ? tty_open+0x6f8/0xbb0 [ 90.850842][ T8951] ? preempt_schedule+0x4b/0x60 [ 90.855757][ T8951] ? ___preempt_schedule+0x16/0x18 [ 90.860855][ T8951] ? trace_hardirqs_on+0x5e/0x240 [ 90.865870][ T8951] ? tty_open+0x6f8/0xbb0 [ 90.870272][ T8951] end_report+0x47/0x4f [ 90.874401][ T8951] ? tty_open+0x6f8/0xbb0 [ 90.878810][ T8951] __kasan_report.cold+0xe/0x41 [ 90.883637][ T8951] ? tty_open+0x6f8/0xbb0 [ 90.887943][ T8951] kasan_report+0x12/0x20 [ 90.892252][ T8951] check_memory_region+0x134/0x1a0 [ 90.897346][ T8951] __kasan_check_read+0x11/0x20 [ 90.902171][ T8951] tty_open+0x6f8/0xbb0 [ 90.906316][ T8951] ? tty_init_dev+0x460/0x460 [ 90.910974][ T8951] ? do_raw_spin_unlock+0x178/0x270 [ 90.916144][ T8951] ? tty_init_dev+0x460/0x460 [ 90.920806][ T8951] chrdev_open+0x245/0x6b0 [ 90.925198][ T8951] ? cdev_put.part.0+0x50/0x50 [ 90.929958][ T8951] ? security_file_open+0x87/0x300 [ 90.935067][ T8951] do_dentry_open+0x4e6/0x1380 [ 90.939814][ T8951] ? __kasan_check_read+0x11/0x20 [ 90.944815][ T8951] ? cdev_put.part.0+0x50/0x50 [ 90.949563][ T8951] ? chown_common+0x5c0/0x5c0 [ 90.954331][ T8951] ? inode_permission+0xb4/0x520 [ 90.959241][ T8951] vfs_open+0xa0/0xd0 [ 90.963219][ T8951] path_openat+0x10e4/0x4710 [ 90.967785][ T8951] ? __kasan_kmalloc.constprop.0+0xcf/0xe0 [ 90.973565][ T8951] ? kasan_slab_alloc+0xf/0x20 [ 90.978325][ T8951] ? kmem_cache_alloc+0x121/0x710 [ 90.983324][ T8951] ? getname_flags+0xd6/0x5b0 [ 90.987991][ T8951] ? getname+0x1a/0x20 [ 90.992065][ T8951] ? do_sys_open+0x2c9/0x5d0 [ 90.996644][ T8951] ? path_lookupat.isra.0+0x8d0/0x8d0 [ 91.001998][ T8951] ? __alloc_fd+0x487/0x620 [ 91.006480][ T8951] do_filp_open+0x1a1/0x280 [ 91.010960][ T8951] ? may_open_dev+0x100/0x100 [ 91.015703][ T8951] ? do_raw_spin_unlock+0x178/0x270 [ 91.020893][ T8951] ? _raw_spin_unlock+0x28/0x40 [ 91.025725][ T8951] ? __alloc_fd+0x487/0x620 [ 91.030208][ T8951] do_sys_open+0x3fe/0x5d0 [ 91.034599][ T8951] ? filp_open+0x80/0x80 [ 91.038817][ T8951] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 91.044249][ T8951] ? do_fast_syscall_32+0xd1/0xe16 [ 91.049338][ T8951] ? entry_SYSENTER_compat+0x70/0x7f [ 91.054612][ T8951] ? do_fast_syscall_32+0xd1/0xe16 [ 91.059699][ T8951] __ia32_compat_sys_open+0x79/0xb0 [ 91.064898][ T8951] do_fast_syscall_32+0x27b/0xe16 [ 91.069903][ T8951] entry_SYSENTER_compat+0x70/0x7f [ 91.074997][ T8951] RIP: 0023:0xf7f89a39 [ 91.079045][ T8951] Code: 00 00 00 89 d3 5b 5e 5f 5d c3 b8 80 96 98 00 eb c4 8b 04 24 c3 8b 1c 24 c3 8b 34 24 c3 8b 3c 24 c3 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90 [ 91.098698][ T8951] RSP: 002b:00000000fff1d018 EFLAGS: 00000246 ORIG_RAX: 0000000000000005 [ 91.107132][ T8951] RAX: ffffffffffffffda RBX: 00000000fff1d05c RCX: 0000000000127200 [ 91.115124][ T8951] RDX: 0000000000000000 RSI: 00000000fff1d05c RDI: 0000000000000000 [ 91.123075][ T8951] RBP: 00000000fff1d4a8 R08: 0000000000000000 R09: 0000000000000000 [ 91.131027][ T8951] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 [ 91.138976][ T8951] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 [ 91.148274][ T8951] Kernel Offset: disabled [ 91.152601][ T8951] Rebooting in 86400 seconds..