[ OK ] Reached target Login Prompts. [ OK ] Reached target Multi-User System. [ OK ] Reached target Graphical Interface. Starting Update UTMP about System Runlevel Changes... [ OK ] Started Update UTMP about System Runlevel Changes. Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.10.13' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 57.752800][ T6833] ================================================================== [ 57.752838][ T6833] BUG: KASAN: use-after-free in vcs_read+0xaa7/0xb40 [ 57.752846][ T6833] Write of size 2 at addr ffff8880a2ab3000 by task syz-executor210/6833 [ 57.752848][ T6833] [ 57.752857][ T6833] CPU: 0 PID: 6833 Comm: syz-executor210 Not tainted 5.9.0-rc1-next-20200821-syzkaller #0 [ 57.752878][ T6833] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 57.752881][ T6833] Call Trace: [ 57.752908][ T6833] dump_stack+0x18f/0x20d [ 57.752917][ T6833] ? vcs_read+0xaa7/0xb40 [ 57.752923][ T6833] ? vcs_read+0xaa7/0xb40 [ 57.752934][ T6833] print_address_description.constprop.0.cold+0xae/0x497 [ 57.752943][ T6833] ? lock_release+0x8e0/0x8e0 [ 57.752951][ T6833] ? lock_downgrade+0x830/0x830 [ 57.752960][ T6833] ? vprintk_func+0x97/0x1a6 [ 57.752968][ T6833] ? vcs_read+0xaa7/0xb40 [ 57.752974][ T6833] ? vcs_read+0xaa7/0xb40 [ 57.752981][ T6833] kasan_report.cold+0x1f/0x37 [ 57.752990][ T6833] ? vcs_read+0xaa7/0xb40 [ 57.752998][ T6833] vcs_read+0xaa7/0xb40 [ 57.753011][ T6833] ? vcs_write+0xb50/0xb50 [ 57.753020][ T6833] ? security_file_permission+0x248/0x560 [ 57.753031][ T6833] ? vcs_write+0xb50/0xb50 [ 57.753039][ T6833] vfs_read+0x1df/0x5a0 [ 57.753049][ T6833] ksys_read+0x12d/0x250 [ 57.753057][ T6833] ? vfs_write+0x730/0x730 [ 57.753066][ T6833] ? trace_hardirqs_on+0x5f/0x220 [ 57.753074][ T6833] ? lockdep_hardirqs_on+0x76/0xf0 [ 57.753084][ T6833] do_syscall_64+0x2d/0x70 [ 57.753093][ T6833] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 57.753115][ T6833] RIP: 0033:0x440249 [ 57.753124][ T6833] Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 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 0f 83 7b 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00 [ 57.753128][ T6833] RSP: 002b:00007ffd87b6ba88 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 [ 57.753137][ T6833] RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440249 [ 57.753158][ T6833] RDX: 0000000000002020 RSI: 0000000020000340 RDI: 0000000000000003 [ 57.753163][ T6833] RBP: 00000000006ca018 R08: 00000000004002c8 R09: 00000000004002c8 [ 57.753169][ T6833] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401a50 [ 57.753174][ T6833] R13: 0000000000401ae0 R14: 0000000000000000 R15: 0000000000000000 [ 57.753184][ T6833] [ 57.753188][ T6833] Allocated by task 6752: [ 57.753196][ T6833] kasan_save_stack+0x1b/0x40 [ 57.753203][ T6833] __kasan_kmalloc.constprop.0+0xbf/0xd0 [ 57.753210][ T6833] kmem_cache_alloc+0x138/0x3a0 [ 57.753218][ T6833] vm_area_dup+0x88/0x2b0 [ 57.753225][ T6833] __split_vma+0xa5/0x560 [ 57.753231][ T6833] split_vma+0x95/0xd0 [ 57.753238][ T6833] mprotect_fixup+0x71c/0x940 [ 57.753254][ T6833] do_mprotect_pkey+0x531/0x940 [ 57.753262][ T6833] __x64_sys_mprotect+0x74/0xb0 [ 57.753269][ T6833] do_syscall_64+0x2d/0x70 [ 57.753277][ T6833] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 57.753279][ T6833] [ 57.753285][ T6833] The buggy address belongs to the object at ffff8880a2ab3000 [ 57.753285][ T6833] which belongs to the cache vm_area_struct of size 200 [ 57.753292][ T6833] The buggy address is located 0 bytes inside of [ 57.753292][ T6833] 200-byte region [ffff8880a2ab3000, ffff8880a2ab30c8) [ 57.753295][ T6833] The buggy address belongs to the page: [ 57.753304][ T6833] page:00000000ff2f3ea3 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff8880a2ab3e70 pfn:0xa2ab3 [ 57.753310][ T6833] flags: 0xfffe0000000200(slab) [ 57.753322][ T6833] raw: 00fffe0000000200 ffffea00027ce148 ffffea00029de708 ffff8880aa06f500 [ 57.753331][ T6833] raw: ffff8880a2ab3e70 ffff8880a2ab3000 0000000100000001 0000000000000000 [ 57.753335][ T6833] page dumped because: kasan: bad access detected [ 57.753337][ T6833] [ 57.753340][ T6833] Memory state around the buggy address: [ 57.753347][ T6833] ffff8880a2ab2f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 57.753353][ T6833] ffff8880a2ab2f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 57.753359][ T6833] >ffff8880a2ab3000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 57.753362][ T6833] ^ [ 57.753368][ T6833] ffff8880a2ab3080: fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc [ 57.753374][ T6833] ffff8880a2ab3100: fc fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 57.753377][ T6833] ================================================================== [ 57.753380][ T6833] Disabling lock debugging due to kernel taint [ 57.753384][ T6833] Kernel panic - not syncing: panic_on_warn set ... [ 57.753392][ T6833] CPU: 0 PID: 6833 Comm: syz-executor210 Tainted: G B 5.9.0-rc1-next-20200821-syzkaller #0 [ 57.753396][ T6833] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 57.753398][ T6833] Call Trace: [ 57.753407][ T6833] dump_stack+0x18f/0x20d [ 57.753414][ T6833] ? vcs_read+0xa40/0xb40 [ 57.753421][ T6833] panic+0x2e3/0x75c [ 57.753429][ T6833] ? __warn_printk+0xf3/0xf3 [ 57.753438][ T6833] ? trace_hardirqs_on+0x55/0x220 [ 57.753445][ T6833] ? vcs_read+0xaa7/0xb40 [ 57.753451][ T6833] ? vcs_read+0xaa7/0xb40 [ 57.753458][ T6833] end_report+0x4d/0x53 [ 57.753465][ T6833] kasan_report.cold+0xd/0x37 [ 57.753472][ T6833] ? vcs_read+0xaa7/0xb40 [ 57.753479][ T6833] vcs_read+0xaa7/0xb40 [ 57.753488][ T6833] ? vcs_write+0xb50/0xb50 [ 57.753496][ T6833] ? security_file_permission+0x248/0x560 [ 57.753504][ T6833] ? vcs_write+0xb50/0xb50 [ 57.753511][ T6833] vfs_read+0x1df/0x5a0 [ 57.753519][ T6833] ksys_read+0x12d/0x250 [ 57.753526][ T6833] ? vfs_write+0x730/0x730 [ 57.753533][ T6833] ? trace_hardirqs_on+0x5f/0x220 [ 57.753540][ T6833] ? lockdep_hardirqs_on+0x76/0xf0 [ 57.753548][ T6833] do_syscall_64+0x2d/0x70 [ 57.753555][ T6833] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 57.753560][ T6833] RIP: 0033:0x440249 [ 57.753567][ T6833] Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 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 0f 83 7b 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00 [ 57.753571][ T6833] RSP: 002b:00007ffd87b6ba88 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 [ 57.753578][ T6833] RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440249 [ 57.753583][ T6833] RDX: 0000000000002020 RSI: 0000000020000340 RDI: 0000000000000003 [ 57.753587][ T6833] RBP: 00000000006ca018 R08: 00000000004002c8 R09: 00000000004002c8 [ 57.753592][ T6833] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401a50 [ 57.753596][ T6833] R13: 0000000000401ae0 R14: 0000000000000000 R15: 0000000000000000 [ 57.754896][ T6833] Kernel Offset: disabled [ 58.392692][ T6833] Rebooting in 86400 seconds..