================================================================== BUG: KASAN: use-after-free in relay_switch_subbuf+0x8be/0x920 kernel/relay.c:755 Read of size 8 at addr ffff88808a7fd5d8 by task syz-executor.2/4714 CPU: 1 PID: 4714 Comm: syz-executor.2 Not tainted 5.3.0-rc6+ #129 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+0x172/0x1f0 lib/dump_stack.c:113 print_address_description.cold+0xd4/0x306 mm/kasan/report.c:351 __kasan_report.cold+0x1b/0x36 mm/kasan/report.c:482 kasan_report+0x12/0x17 mm/kasan/common.c:618 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132 relay_switch_subbuf+0x8be/0x920 kernel/relay.c:755 relay_reserve include/linux/relay.h:261 [inline] trace_note.isra.0+0x5b8/0x6e0 kernel/trace/blktrace.c:93 trace_note_tsk kernel/trace/blktrace.c:124 [inline] __blk_add_trace+0xb70/0xe10 kernel/trace/blktrace.c:264 blk_add_trace_bio_remap+0x392/0x510 kernel/trace/blktrace.c:1005 trace_block_bio_remap include/trace/events/block.h:559 [inline] blk_partition_remap block/blk-core.c:851 [inline] generic_make_request_checks+0x152b/0x21a0 block/blk-core.c:891 generic_make_request+0x8f/0xb50 block/blk-core.c:1006 submit_bio+0x104/0x4d0 block/blk-core.c:1163 submit_bh_wbc+0x6b6/0x900 fs/buffer.c:3095 submit_bh fs/buffer.c:3101 [inline] __sync_dirty_buffer+0x12b/0x350 fs/buffer.c:3187 sync_dirty_buffer+0x1b/0x20 fs/buffer.c:3200 __ext4_handle_dirty_metadata+0x241/0x600 fs/ext4/ext4_jbd2.c:300 ext4_handle_dirty_dirblock+0x3ae/0x4c0 fs/ext4/namei.c:404 add_dirent_to_buf+0x410/0x690 fs/ext4/namei.c:2026 ext4_add_entry+0x6a2/0xdf0 fs/ext4/namei.c:2225 ext4_add_nondir+0x28/0x90 fs/ext4/namei.c:2553 ext4_create+0x2dc/0x5e0 fs/ext4/namei.c:2595 lookup_open+0x12be/0x1a50 fs/namei.c:3232 do_last fs/namei.c:3322 [inline] path_openat+0x14ac/0x4630 fs/namei.c:3533 do_filp_open+0x1a1/0x280 fs/namei.c:3563 do_sys_open+0x3fe/0x5d0 fs/open.c:1089 __do_sys_open fs/open.c:1107 [inline] __se_sys_open fs/open.c:1102 [inline] __x64_sys_open+0x7e/0xc0 fs/open.c:1102 do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x459879 Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f09a9593c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459879 RDX: 0000000000000000 RSI: 000000000000027a RDI: 00000000200013c0 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f09a95946d4 R13: 00000000004c5fcb R14: 00000000004daca8 R15: 00000000ffffffff Allocated by task 3564: save_stack+0x23/0x90 mm/kasan/common.c:69 set_track mm/kasan/common.c:77 [inline] __kasan_kmalloc mm/kasan/common.c:493 [inline] __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:466 kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:501 slab_post_alloc_hook mm/slab.h:520 [inline] slab_alloc mm/slab.c:3319 [inline] kmem_cache_alloc+0x121/0x710 mm/slab.c:3483 alloc_inode+0x16f/0x1e0 fs/inode.c:229 new_inode_pseudo+0x19/0xf0 fs/inode.c:916 new_inode+0x1f/0x40 fs/inode.c:945 debugfs_get_inode+0x1a/0x130 fs/debugfs/inode.c:40 __debugfs_create_file+0xb7/0x3c0 fs/debugfs/inode.c:362 debugfs_create_file+0x5a/0x70 fs/debugfs/inode.c:413 kvm_create_vm_debugfs arch/x86/kvm/../../../virt/kvm/kvm_main.c:621 [inline] kvm_dev_ioctl_create_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:3462 [inline] kvm_dev_ioctl+0xa04/0x1650 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3489 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:509 [inline] do_vfs_ioctl+0xdb6/0x13e0 fs/ioctl.c:696 ksys_ioctl+0xab/0xd0 fs/ioctl.c:713 __do_sys_ioctl fs/ioctl.c:720 [inline] __se_sys_ioctl fs/ioctl.c:718 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718 do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 9: save_stack+0x23/0x90 mm/kasan/common.c:69 set_track mm/kasan/common.c:77 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/common.c:455 kasan_slab_free+0xe/0x10 mm/kasan/common.c:463 __cache_free mm/slab.c:3425 [inline] kmem_cache_free+0x86/0x320 mm/slab.c:3693 free_inode_nonrcu+0x1d/0x30 fs/inode.c:208 debugfs_free_inode+0x56/0xa0 fs/debugfs/inode.c:173 i_callback+0x44/0x80 fs/inode.c:216 __rcu_reclaim kernel/rcu/rcu.h:222 [inline] rcu_do_batch kernel/rcu/tree.c:2114 [inline] rcu_core+0x67f/0x1580 kernel/rcu/tree.c:2314 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2323 __do_softirq+0x262/0x98c kernel/softirq.c:292 The buggy address belongs to the object at ffff88808a7fd560 which belongs to the cache inode_cache(49:syz3) of size 928 The buggy address is located 120 bytes inside of 928-byte region [ffff88808a7fd560, ffff88808a7fd900) The buggy address belongs to the page: page:ffffea000229ff40 refcount:1 mapcount:0 mapping:ffff8880936f51c0 index:0xffff88808a7fdffd flags: 0x1fffc0000000200(slab) raw: 01fffc0000000200 ffffea0001810808 ffffea000181a648 ffff8880936f51c0 raw: ffff88808a7fdffd ffff88808a7fd140 0000000100000003 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88808a7fd480: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ffff88808a7fd500: fc fc fc fc fc fc fc fc fc fc fc fc fb fb fb fb >ffff88808a7fd580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88808a7fd600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88808a7fd680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================