================================================================== BUG: KASAN: use-after-free in relay_switch_subbuf+0x8be/0x920 kernel/relay.c:755 Read of size 8 at addr ffff8880414f2cf8 by task syz-executor.2/31861 CPU: 0 PID: 31861 Comm: syz-executor.2 Not tainted 5.3.0-rc6 #146 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.isra.0+0x19c/0x220 kernel/trace/blktrace.c:865 blk_add_trace_bio_queue+0x46/0x60 kernel/trace/blktrace.c:902 trace_block_bio_queue include/trace/events/block.h:357 [inline] generic_make_request_checks+0x16c3/0x21a0 block/blk-core.c:954 generic_make_request+0x8f/0xb50 block/blk-core.c:1006 submit_bio+0x104/0x4d0 block/blk-core.c:1163 blk_next_bio+0x4a/0x60 block/blk-lib.c:19 __blkdev_issue_zero_pages+0x151/0x430 block/blk-lib.c:284 blkdev_issue_zeroout+0x434/0x4c0 block/blk-lib.c:378 blk_ioctl_zeroout block/ioctl.c:264 [inline] blkdev_ioctl+0x13d4/0x1c1a block/ioctl.c:531 block_ioctl+0xee/0x130 fs/block_dev.c:1954 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 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:00007f8cfa4fec78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459879 RDX: 0000000020000080 RSI: 000000000000127f RDI: 0000000000000008 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f8cfa4ff6d4 R13: 00000000004c0f8b R14: 00000000004d41b0 R15: 00000000ffffffff Allocated by task 18724: 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 __d_alloc+0x2e/0x8c0 fs/dcache.c:1688 d_alloc_anon fs/dcache.c:1786 [inline] d_alloc_cursor+0x3f/0xe0 fs/dcache.c:1792 dcache_dir_open+0x37/0x90 fs/libfs.c:78 do_dentry_open+0x4df/0x1250 fs/open.c:797 vfs_open+0xa0/0xd0 fs/open.c:906 do_last fs/namei.c:3416 [inline] path_openat+0x10e9/0x4630 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 Freed by task 22113: 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 __d_free+0x20/0x30 fs/dcache.c:271 __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 ffff8880414f2ca0 which belongs to the cache dentry(49:syz2) of size 288 The buggy address is located 88 bytes inside of 288-byte region [ffff8880414f2ca0, ffff8880414f2dc0) The buggy address belongs to the page: page:ffffea0001053c80 refcount:1 mapcount:0 mapping:ffff88808dcba700 index:0xffff8880414f2300 flags: 0x1fffc0000000200(slab) raw: 01fffc0000000200 ffffea0001051188 ffffea00024ada88 ffff88808dcba700 raw: ffff8880414f2300 ffff8880414f2040 0000000100000008 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8880414f2b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880414f2c00: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc >ffff8880414f2c80: fc fc fc fc fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8880414f2d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880414f2d80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ==================================================================