RDX: ffffffffffffffef RSI: 0000000020d7cfcb RDI: 0000000000000008 RBP: 000000000075bf20 R08: 0000000000000000 R09: fffffffffffffed7 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f7b6218e6d4 R13: 00000000004c8c14 R14: 00000000004df288 R15: 0000000000000009 ================================================================== BUG: KASAN: use-after-free in relay_switch_subbuf+0x87c/0x8e0 kernel/relay.c:754 Read of size 8 at addr ffff888089bb34b8 by task syz-executor.4/11448 CPU: 1 PID: 11448 Comm: syz-executor.4 Not tainted 4.14.155-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x142/0x197 lib/dump_stack.c:58 print_address_description.cold+0x7c/0x1dc mm/kasan/report.c:252 kasan_report_error mm/kasan/report.c:351 [inline] kasan_report mm/kasan/report.c:409 [inline] kasan_report.cold+0xa9/0x2af mm/kasan/report.c:393 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430 relay_switch_subbuf+0x87c/0x8e0 kernel/relay.c:754 relay_flush kernel/relay.c:882 [inline] relay_flush+0x1ae/0x270 kernel/relay.c:866 blk_trace_startstop+0x203/0x5c0 kernel/trace/blktrace.c:657 blk_trace_ioctl+0x1b1/0x270 kernel/trace/blktrace.c:705 blkdev_ioctl+0x100/0x1860 block/ioctl.c:580 block_ioctl+0xde/0x120 fs/block_dev.c:1881 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x7ae/0x1060 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x45a639 RSP: 002b:00007f64c6418c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a639 RDX: 0000000000000000 RSI: 0000000000001275 RDI: 000000000000000a RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f64c64196d4 R13: 00000000004c200f R14: 00000000004d5dd8 R15: 00000000ffffffff Allocated by task 11448: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59 save_stack+0x45/0xd0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] kasan_kmalloc mm/kasan/kasan.c:551 [inline] kasan_kmalloc+0xce/0xf0 mm/kasan/kasan.c:529 kasan_slab_alloc+0xf/0x20 mm/kasan/kasan.c:489 kmem_cache_alloc+0x12e/0x780 mm/slab.c:3552 __d_alloc+0x2d/0x9f0 fs/dcache.c:1623 d_alloc+0x4d/0x270 fs/dcache.c:1710 __lookup_hash fs/namei.c:1570 [inline] __lookup_hash+0x58/0x180 fs/namei.c:1562 lookup_one_len+0x27b/0x3a0 fs/namei.c:2538 start_creating fs/debugfs/inode.c:314 [inline] start_creating+0xa6/0x1b0 fs/debugfs/inode.c:290 __debugfs_create_file+0x53/0x3d0 fs/debugfs/inode.c:353 debugfs_create_file+0x5a/0x70 fs/debugfs/inode.c:404 blk_create_buf_file_callback+0x33/0x40 kernel/trace/blktrace.c:445 relay_create_buf_file+0xf1/0x160 kernel/relay.c:427 relay_open_buf.part.0+0x6a9/0x9e0 kernel/relay.c:456 relay_open_buf kernel/relay.c:448 [inline] relay_open kernel/relay.c:598 [inline] relay_open+0x4e7/0x920 kernel/relay.c:562 do_blk_trace_setup+0x3ca/0xb10 kernel/trace/blktrace.c:533 blk_trace_setup+0xbd/0x140 kernel/trace/blktrace.c:579 blk_trace_ioctl+0x147/0x270 kernel/trace/blktrace.c:694 blkdev_ioctl+0x100/0x1860 block/ioctl.c:580 block_ioctl+0xde/0x120 fs/block_dev.c:1881 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x7ae/0x1060 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 Freed by task 7: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59 save_stack+0x45/0xd0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] kasan_slab_free+0x75/0xc0 mm/kasan/kasan.c:524 __cache_free mm/slab.c:3496 [inline] kmem_cache_free+0x83/0x2b0 mm/slab.c:3758 __d_free+0x20/0x30 fs/dcache.c:270 __rcu_reclaim kernel/rcu/rcu.h:195 [inline] rcu_do_batch kernel/rcu/tree.c:2699 [inline] invoke_rcu_callbacks kernel/rcu/tree.c:2962 [inline] __rcu_process_callbacks kernel/rcu/tree.c:2929 [inline] rcu_process_callbacks+0x7b8/0x12b0 kernel/rcu/tree.c:2946 __do_softirq+0x244/0x9a0 kernel/softirq.c:288 The buggy address belongs to the object at ffff888089bb3460 which belongs to the cache dentry of size 288 The buggy address is located 88 bytes inside of 288-byte region [ffff888089bb3460, ffff888089bb3580) The buggy address belongs to the page: page:ffffea000226ecc0 count:1 mapcount:0 mapping:ffff888089bb3040 index:0x0 flags: 0x1fffc0000000100(slab) raw: 01fffc0000000100 ffff888089bb3040 0000000000000000 000000010000000b raw: ffffea00029dcea0 ffffea00020421e0 ffff88821f8b5680 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888089bb3380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888089bb3400: fb fb fb fb fc fc fc fc fc fc fc fc fb fb fb fb >ffff888089bb3480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888089bb3500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888089bb3580: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb ==================================================================