bisecting fixing commit since 4d552acf337038028f7e2f63a927afb7adf65fc1 building syzkaller on 505ab413c77ce8c6bd4658ea5e68ea2534d47b39 testing commit 4d552acf337038028f7e2f63a927afb7adf65fc1 with gcc (GCC) 8.1.0 kernel signature: 92882a2e6aaa632bb16c305a6414de4f6e926d57 run #0: crashed: KASAN: use-after-free Read in __vb2_perform_fileio run #1: crashed: KASAN: use-after-free Read in __vb2_perform_fileio run #2: crashed: INFO: task hung in vivid_stop_generating_vid_cap run #3: crashed: INFO: task hung in vivid_stop_generating_vid_cap run #4: crashed: INFO: task hung in vivid_stop_generating_vid_cap run #5: crashed: INFO: task hung in vivid_stop_generating_vid_cap run #6: crashed: INFO: task hung in vivid_stop_generating_vid_cap run #7: crashed: INFO: task hung in vivid_stop_generating_vid_cap run #8: crashed: INFO: task hung in vivid_stop_generating_vid_cap run #9: crashed: INFO: task hung in vivid_stop_generating_vid_cap testing current HEAD 14260788bbb9c94b0e36abc17294266b69dd46e4 testing commit 14260788bbb9c94b0e36abc17294266b69dd46e4 with gcc (GCC) 8.1.0 kernel signature: 1adc4033f40633968fea0b1c26ec2608d81bb63f run #0: boot failed: create image operation failed: &{Code:QUOTA_EXCEEDED Location: Message:Quota 'CPUS' exceeded. Limit: 500.0 in region us-central1. ForceSendFields:[] NullFields:[]}. run #1: crashed: INFO: task hung in vivid_stop_generating_vid_cap run #2: crashed: INFO: task hung in vivid_stop_generating_vid_cap run #3: crashed: INFO: task hung in vivid_stop_generating_vid_cap run #4: crashed: INFO: task hung in vivid_stop_generating_vid_cap run #5: crashed: INFO: task hung in vivid_stop_generating_vid_cap run #6: crashed: INFO: task hung in vivid_stop_generating_vid_cap run #7: crashed: INFO: task hung in vivid_stop_generating_vid_cap run #8: crashed: INFO: task hung in vivid_stop_generating_vid_cap run #9: crashed: INFO: task hung in vivid_stop_generating_vid_cap revisions tested: 2, total time: 30m30.566680906s (build: 16m43.735511793s, test: 12m50.904628842s) the crash still happens on HEAD commit msg: Linux 4.19.86 crash: INFO: task hung in vivid_stop_generating_vid_cap IPv6: ADDRCONF(NETDEV_CHANGE): hsr_slave_1: link becomes ready IPv6: ADDRCONF(NETDEV_UP): vxcan1: link is not ready 8021q: adding VLAN 0 to HW filter on device batadv0 INFO: task syz-executor.0:7210 blocked for more than 140 seconds. Not tainted 4.19.86-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.0 D28136 7210 7079 0x00000004 Call Trace: context_switch kernel/sched/core.c:2826 [inline] __schedule+0x792/0x1c20 kernel/sched/core.c:3515 schedule+0x7f/0x1b0 kernel/sched/core.c:3559 schedule_timeout+0x6d7/0xda0 kernel/time/timer.c:1782 do_wait_for_common kernel/sched/completion.c:83 [inline] __wait_for_common kernel/sched/completion.c:104 [inline] wait_for_common kernel/sched/completion.c:115 [inline] wait_for_completion+0x282/0x460 kernel/sched/completion.c:136 kthread_stop+0xc9/0x4c0 kernel/kthread.c:550 vivid_stop_generating_vid_cap+0x191/0x5fe drivers/media/platform/vivid/vivid-kthread-cap.c:922 vid_cap_stop_streaming+0x75/0xd0 drivers/media/platform/vivid/vivid-vid-cap.c:256 __vb2_queue_cancel+0x99/0x6f0 drivers/media/common/videobuf2/videobuf2-core.c:1682 vb2_core_streamoff+0x48/0x110 drivers/media/common/videobuf2/videobuf2-core.c:1816 __vb2_cleanup_fileio+0x69/0x140 drivers/media/common/videobuf2/videobuf2-core.c:2343 vb2_core_queue_release+0xf/0x70 drivers/media/common/videobuf2/videobuf2-core.c:2070 vb2_queue_release drivers/media/common/videobuf2/videobuf2-v4l2.c:671 [inline] _vb2_fop_release+0x1ac/0x280 drivers/media/common/videobuf2/videobuf2-v4l2.c:842 vb2_fop_release+0x66/0xd0 drivers/media/common/videobuf2/videobuf2-v4l2.c:856 vivid_fop_release+0x15f/0x3a0 drivers/media/platform/vivid/vivid-core.c:474 v4l2_release+0xee/0x1a0 drivers/media/v4l2-core/v4l2-dev.c:448 __fput+0x24c/0x7f0 fs/file_table.c:278 ____fput+0x9/0x10 fs/file_table.c:309 task_work_run+0x10e/0x190 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:193 [inline] exit_to_usermode_loop+0x1a9/0x200 arch/x86/entry/common.c:167 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline] syscall_return_slowpath arch/x86/entry/common.c:271 [inline] do_syscall_64+0x419/0x4e0 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4129e1 Code: 00 00 00 e8 c1 02 00 00 48 8b 84 24 80 00 00 00 48 8b 4c 24 28 48 0f af c1 48 8b 4c 24 78 48 01 c8 48 c1 e8 03 48 83 c0 03 48 e8 02 48 8b 8c 24 90 00 00 00 48 c1 e9 05 48 8b 54 24 68 48 89 RSP: 002b:00007fff084a4bc0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000004 RCX: 00000000004129e1 RDX: 0000001b2e020000 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 0000000000740458 R08: 000000000000e463 R09: 000000000000e463 R10: 00007fff084a4c90 R11: 0000000000000293 R12: 0000000000000001 R13: 000000000000e466 R14: 000000000000e493 R15: 000000000073bf0c Showing all locks held in the system: 1 lock held by khungtaskd/1021: #0: 0000000055dea56e (rcu_read_lock){....}, at: debug_show_all_locks+0x5b/0x27a kernel/locking/lockdep.c:4438 2 locks held by getty/6959: #0: 00000000c1bdb794 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x2d/0x40 drivers/tty/tty_ldsem.c:362 #1: 0000000064cf1789 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x1ee/0x18d0 drivers/tty/n_tty.c:2154 2 locks held by getty/6960: #0: 0000000009556b91 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x2d/0x40 drivers/tty/tty_ldsem.c:362 #1: 00000000c35bd7cd (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x1ee/0x18d0 drivers/tty/n_tty.c:2154 2 locks held by getty/6961: #0: 00000000e07542b9 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x2d/0x40 drivers/tty/tty_ldsem.c:362 #1: 00000000b188fd02 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x1ee/0x18d0 drivers/tty/n_tty.c:2154 2 locks held by getty/6962: #0: 00000000b6279b92 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x2d/0x40 drivers/tty/tty_ldsem.c:362 #1: 0000000087f17edc (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x1ee/0x18d0 drivers/tty/n_tty.c:2154 2 locks held by getty/6963: #0: 000000006629b483 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x2d/0x40 drivers/tty/tty_ldsem.c:362 #1: 0000000039d822cb (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x1ee/0x18d0 drivers/tty/n_tty.c:2154 2 locks held by getty/6964: #0: 0000000089fde01f (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x2d/0x40 drivers/tty/tty_ldsem.c:362 #1: 000000009fd39084 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x1ee/0x18d0 drivers/tty/n_tty.c:2154 2 locks held by getty/6965: #0: 0000000046378f48 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x2d/0x40 drivers/tty/tty_ldsem.c:362 #1: 000000005f5a594c (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x1ee/0x18d0 drivers/tty/n_tty.c:2154 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1021 Comm: khungtaskd Not tainted 4.19.86-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x123/0x177 lib/dump_stack.c:118 nmi_cpu_backtrace.cold.3+0x3e/0x76 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0xf5/0x119 lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:203 [inline] watchdog+0x5c3/0xb40 kernel/hung_task.c:287 kthread+0x327/0x3f0 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:415 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 32 Comm: kworker/u4:2 Not tainted 4.19.86-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: bat_events batadv_nc_worker RIP: 0010:check_memory_region+0x21/0x1b0 mm/kasan/kasan.c:266 Code: 2e 0f 1f 84 00 00 00 00 00 48 85 f6 0f 84 3c 01 00 00 48 b8 ff ff ff ff ff 7f ff ff 55 0f b6 d2 48 39 c7 48 89 e5 41 55 41 54 <53> 0f 86 11 01 00 00 4c 8d 5c 37 ff 48 89 fb 49 b9 00 00 00 00 00 RSP: 0018:ffff8880a996fca8 EFLAGS: 00000212 RAX: ffff7fffffffffff RBX: ffff8880aea23980 RCX: ffffffff815278b1 RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff8880aea23990 RBP: ffff8880a996fcb8 R08: ffffed1015d44733 R09: ffffed1015d44732 R10: ffffed1015d44732 R11: ffff8880aea23993 R12: ffff8880aea23990 R13: 0000000000000305 R14: 0000000000000000 R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f74561a6140 CR3: 000000007d9f5000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: kasan_check_read+0x11/0x20 mm/kasan/kasan.c:272 atomic_read include/asm-generic/atomic-instrumented.h:21 [inline] rcu_dynticks_curr_cpu_in_eqs+0x51/0xb0 kernel/rcu/tree.c:350 rcu_is_watching+0x10/0x30 kernel/rcu/tree.c:1025 rcu_read_unlock include/linux/rcupdate.h:677 [inline] batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:423 [inline] batadv_nc_worker+0x3a9/0x630 net/batman-adv/network-coding.c:730 process_one_work+0x835/0x1670 kernel/workqueue.c:2153 worker_thread+0x85/0xb60 kernel/workqueue.c:2296 kthread+0x327/0x3f0 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:415