*** Guest State *** CR0: actual=0x0000000000000030, shadow=0x0000000060000010, gh_mask=fffffffffffffff7 CR4: actual=0x0000000000002040, shadow=0x0000000000000000, gh_mask=ffffffffffffe871 ================================================================== BUG: KASAN: use-after-free in relay_switch_subbuf+0xa0e/0xa70 kernel/relay.c:753 CR3 = 0x0000000000000000 Read of size 8 at addr ffff8881d5423738 by task syz-executor3/5366 CPU: 1 PID: 5366 Comm: syz-executor3 Not tainted 4.20.0-rc7+ #379 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+0x244/0x39d lib/dump_stack.c:113 RSP = 0x0000000000000000 RIP = 0x0000000000000000 print_address_description.cold.7+0x9/0x1ff mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report.cold.8+0x242/0x309 mm/kasan/report.c:412 RFLAGS=0x0001a202 DR7 = 0x0000000000000400 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433 relay_switch_subbuf+0xa0e/0xa70 kernel/relay.c:753 relay_flush+0x1c6/0x280 kernel/relay.c:881 Sysenter RSP=0000000000000000 CS:RIP=0000:0000000000000000 __blk_trace_startstop.isra.21+0x2ae/0x8c0 kernel/trace/blktrace.c:668 CS: sel=0xf000, attr=0x0009b, limit=0x0000ffff, base=0x00000000ffff0000 DS: sel=0x0000, attr=0x00093, limit=0x0000ffff, base=0x0000000000000000 blk_trace_ioctl+0x226/0x2f0 kernel/trace/blktrace.c:727 blkdev_ioctl+0xb45/0x21b0 block/ioctl.c:591 SS: sel=0x0000, attr=0x00093, limit=0x0000ffff, base=0x0000000000000000 ES: sel=0x0000, attr=0x00093, limit=0x0000ffff, base=0x0000000000000000 FS: sel=0x0000, attr=0x00093, limit=0x0000ffff, base=0x0000000000000000 block_ioctl+0xee/0x130 fs/block_dev.c:1883 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:509 [inline] do_vfs_ioctl+0x1de/0x1790 fs/ioctl.c:696 GS: sel=0x0000, attr=0x00093, limit=0x0000ffff, base=0x0000000000000000 GDTR: limit=0x0000ffff, base=0x0000000000000000 ksys_ioctl+0xa9/0xd0 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+0x1b9/0x820 arch/x86/entry/common.c:290 LDTR: sel=0x0000, attr=0x00082, limit=0x0000ffff, base=0x0000000000000000 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x457669 IDTR: limit=0x0000ffff, base=0x0000000000000000 Code: fd b3 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 b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fc7b92bac78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457669 RDX: 0000000000000000 RSI: 0000000000001275 RDI: 0000000000000006 RBP: 000000000072bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fc7b92bb6d4 R13: 00000000004bec6e R14: 00000000004cf958 R15: 00000000ffffffff Allocated by task 5366: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490 kmem_cache_alloc+0x12e/0x730 mm/slab.c:3554 __d_alloc+0xc8/0xb90 fs/dcache.c:1599 d_alloc+0x96/0x380 fs/dcache.c:1678 d_alloc_parallel+0x15a/0x1f40 fs/dcache.c:2421 __lookup_slow+0x1e6/0x540 fs/namei.c:1654 TR: sel=0x0000, attr=0x0008b, limit=0x0000ffff, base=0x0000000000000000 lookup_one_len+0x1d8/0x220 fs/namei.c:2543 start_creating+0xc6/0x200 fs/debugfs/inode.c:308 __debugfs_create_file+0x63/0x400 fs/debugfs/inode.c:347 debugfs_create_file+0x57/0x70 fs/debugfs/inode.c:399 blk_create_buf_file_callback+0x33/0x40 kernel/trace/blktrace.c:444 EFER = 0x0000000000000000 PAT = 0x0007040600070406 relay_create_buf_file+0xf6/0x150 kernel/relay.c:428 relay_open_buf.part.10+0x753/0xb20 kernel/relay.c:455 relay_open_buf kernel/relay.c:447 [inline] relay_open+0x5e5/0xac0 kernel/relay.c:597 do_blk_trace_setup+0x4fe/0xdb0 kernel/trace/blktrace.c:532 __blk_trace_setup+0xd5/0x180 kernel/trace/blktrace.c:577 blk_trace_ioctl+0x17a/0x2f0 kernel/trace/blktrace.c:716 blkdev_ioctl+0xb45/0x21b0 block/ioctl.c:591 block_ioctl+0xee/0x130 fs/block_dev.c:1883 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:509 [inline] do_vfs_ioctl+0x1de/0x1790 fs/ioctl.c:696 ksys_ioctl+0xa9/0xd0 fs/ioctl.c:713 DebugCtl = 0x0000000000000000 DebugExceptions = 0x0000000000000000 __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+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 9: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 __cache_free mm/slab.c:3498 [inline] kmem_cache_free+0x83/0x290 mm/slab.c:3760 __d_free+0x20/0x30 fs/dcache.c:257 __rcu_reclaim kernel/rcu/rcu.h:240 [inline] rcu_do_batch kernel/rcu/tree.c:2437 [inline] invoke_rcu_callbacks kernel/rcu/tree.c:2716 [inline] rcu_process_callbacks+0x100a/0x1ac0 kernel/rcu/tree.c:2697 Interruptibility = 00000000 ActivityState = 00000000 __do_softirq+0x308/0xb7e kernel/softirq.c:292 The buggy address belongs to the object at ffff8881d54236e0 which belongs to the cache dentry(67:syz3) of size 288 The buggy address is located 88 bytes inside of 288-byte region [ffff8881d54236e0, ffff8881d5423800) The buggy address belongs to the page: page:ffffea00075508c0 count:1 mapcount:0 mapping:ffff8881d3203d80 index:0xffff8881d5423dc0 flags: 0x2fffc0000000200(slab) raw: 02fffc0000000200 ffffea0007315f48 ffffea0005db2308 ffff8881d3203d80 raw: ffff8881d5423dc0 ffff8881d5423000 0000000100000005 ffff8881c42f6380 page dumped because: kasan: bad access detected page->mem_cgroup:ffff8881c42f6380 Memory state around the buggy address: ffff8881d5423600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881d5423680: fb fb fb fb fc fc fc fc fc fc fc fc fb fb fb fb *** Host State *** >ffff8881d5423700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8881d5423780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb RIP = 0xffffffff8120495e RSP = 0xffff8881404ef390 ffff8881d5423800: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00 ================================================================== kobject: 'loop1' (000000002bc7d385): kobject_uevent_env