bisecting fixing commit since f6d5cb9e2c06f7d583dd9f4f7cca21d13d78c32a building syzkaller on abf9ba4fc75d9b29af15625d44dcfc1360fad3b7 testing commit f6d5cb9e2c06f7d583dd9f4f7cca21d13d78c32a with gcc (GCC) 8.1.0 kernel signature: a78943baf80b601cdf1e8c898110f263d6a4fca90fa8fa84d7c43da6d11cf32d run #0: crashed: general protection fault in debugfs_remove run #1: crashed: WARNING: bad unlock balance detected! run #2: crashed: KASAN: use-after-free Read in debugfs_remove run #3: crashed: KASAN: use-after-free Read in debugfs_remove run #4: crashed: general protection fault in debugfs_remove run #5: crashed: KASAN: use-after-free Read in debugfs_remove run #6: crashed: KASAN: use-after-free Read in debugfs_remove run #7: crashed: KASAN: use-after-free Read in debugfs_remove run #8: crashed: KASAN: use-after-free Read in debugfs_remove run #9: crashed: KASAN: use-after-free Read in debugfs_remove testing current HEAD b09c34517e1ac4018e3bb75ed5c8610a8a1f486b testing commit b09c34517e1ac4018e3bb75ed5c8610a8a1f486b with gcc (GCC) 8.1.0 kernel signature: 9e7173fa7fe9ec658b81ec6a5e4225465fd282f2a6d64a5afc0b752dbf8c231b run #0: crashed: KASAN: use-after-free Read in debugfs_remove run #1: crashed: KASAN: use-after-free Read in debugfs_remove run #2: crashed: KASAN: use-after-free Read in debugfs_remove run #3: crashed: KASAN: use-after-free Read in debugfs_remove run #4: crashed: KASAN: use-after-free Read in debugfs_remove run #5: crashed: KASAN: use-after-free Read in debugfs_remove run #6: crashed: general protection fault in debugfs_remove run #7: crashed: KASAN: use-after-free Read in debugfs_remove run #8: crashed: KASAN: use-after-free Read in debugfs_remove run #9: crashed: KASAN: use-after-free Read in debugfs_remove revisions tested: 2, total time: 26m54.968632138s (build: 19m21.399161377s, test: 6m44.950348458s) the crash still happens on HEAD commit msg: Linux 4.19.149 crash: KASAN: use-after-free Read in debugfs_remove blktrace: Concurrent blktraces are not allowed on loop0 blktrace: Concurrent blktraces are not allowed on loop0 blktrace: Concurrent blktraces are not allowed on loop0 blktrace: Concurrent blktraces are not allowed on loop0 ================================================================== BUG: KASAN: use-after-free in debugfs_remove+0xd3/0xf0 fs/debugfs/inode.c:687 Read of size 8 at addr ffff88808304e4a0 by task kworker/0:3/3719 CPU: 0 PID: 3719 Comm: kworker/0:3 Not tainted 4.19.149-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events __blk_release_queue Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x17c/0x22a lib/dump_stack.c:118 print_address_description.cold.6+0x9/0x211 mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report.cold.7+0x242/0x307 mm/kasan/report.c:412 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433 debugfs_remove+0xd3/0xf0 fs/debugfs/inode.c:687 blk_trace_free+0x30/0x130 kernel/trace/blktrace.c:315 blk_trace_cleanup kernel/trace/blktrace.c:343 [inline] __blk_trace_remove+0x5c/0x80 kernel/trace/blktrace.c:356 blk_trace_shutdown+0x67/0xc0 kernel/trace/blktrace.c:780 __blk_release_queue+0x1f6/0x490 block/blk-sysfs.c:855 process_one_work+0x7b9/0x15a0 kernel/workqueue.c:2155 worker_thread+0x85/0xb60 kernel/workqueue.c:2298 kthread+0x347/0x410 kernel/kthread.c:259 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 Allocated by task 15751: save_stack mm/kasan/kasan.c:448 [inline] set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc.part.1+0x62/0xf0 mm/kasan/kasan.c:553 kasan_kmalloc+0xaf/0xc0 mm/kasan/kasan.c:538 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490 kmem_cache_alloc+0x12e/0x390 mm/slab.c:3559 __d_alloc+0x28/0xa30 fs/dcache.c:1612 d_alloc+0x42/0x210 fs/dcache.c:1696 d_alloc_parallel+0xf3/0x1570 fs/dcache.c:2443 __lookup_slow+0x18d/0x3f0 fs/namei.c:1655 lookup_one_len+0x132/0x160 fs/namei.c:2544 start_creating+0x91/0x190 fs/debugfs/inode.c:313 __debugfs_create_file+0x37/0x390 fs/debugfs/inode.c:352 debugfs_create_file+0x24/0x30 fs/debugfs/inode.c:404 do_blk_trace_setup+0x365/0xb50 kernel/trace/blktrace.c:554 __blk_trace_setup+0xb4/0x130 kernel/trace/blktrace.c:603 blk_trace_ioctl+0x151/0x270 kernel/trace/blktrace.c:744 blkdev_ioctl+0x71d/0x1790 block/ioctl.c:587 block_ioctl+0xd7/0x130 fs/block_dev.c:1906 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:501 [inline] do_vfs_ioctl+0x196/0x10c0 fs/ioctl.c:688 ksys_ioctl+0x62/0x90 fs/ioctl.c:705 __do_sys_ioctl fs/ioctl.c:712 [inline] __se_sys_ioctl fs/ioctl.c:710 [inline] __x64_sys_ioctl+0x6e/0xb0 fs/ioctl.c:710 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 18: save_stack mm/kasan/kasan.c:448 [inline] set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0x13c/0x220 mm/kasan/kasan.c:521 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 __cache_free mm/slab.c:3503 [inline] kmem_cache_free+0x83/0x290 mm/slab.c:3765 __d_free+0x17/0x20 fs/dcache.c:257 __rcu_reclaim kernel/rcu/rcu.h:236 [inline] rcu_do_batch kernel/rcu/tree.c:2584 [inline] invoke_rcu_callbacks kernel/rcu/tree.c:2897 [inline] __rcu_process_callbacks kernel/rcu/tree.c:2864 [inline] rcu_process_callbacks+0x93a/0x19b0 kernel/rcu/tree.c:2881 __do_softirq+0x25e/0x92d kernel/softirq.c:292 The buggy address belongs to the object at ffff88808304e460 which belongs to the cache dentry of size 288 The buggy address is located 64 bytes inside of 288-byte region [ffff88808304e460, ffff88808304e580) The buggy address belongs to the page: page:ffffea00020c1380 count:1 mapcount:0 mapping:ffff8880aa4b86c0 index:0x0 flags: 0xfffe0000000100(slab) raw: 00fffe0000000100 ffffea00020c14c8 ffffea0002091888 ffff8880aa4b86c0 raw: 0000000000000000 ffff88808304e040 000000010000000b 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88808304e380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88808304e400: fb fb fb fb fc fc fc fc fc fc fc fc fb fb fb fb >ffff88808304e480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88808304e500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88808304e580: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb ==================================================================